fmt/ChangeLog.md
2020-07-04 15:14:42 -07:00

90 KiB

7.0.0 - TBD

  • Reduced the library size. For example, on macOS the stripped binary statically linked with {fmt} shrank from ~368k to less than 100k <http://www.zverovich.net/2020/05/21/reducing-library-size.html>_.

  • Added a simpler and more efficient format string compilation API <https://fmt.dev/dev/api.html#compile-api>_:

    .. code:: c++

    #include <fmt/compile.h>

    // Converts 42 into std::string using the most efficient method and no // runtime format string processing. std::string s = fmt::format(FMT_COMPILE("{}"), 42);

    The old fmt::compile API is now deprecated.

  • Optimized integer formatting: format_to with format string compilation and a stack-allocated buffer is now faster than to_chars on both libc++ and libstdc++ <http://www.zverovich.net/2020/06/13/fast-int-to-string-revisited.html>_.

  • Applied extern templates to improve compile times when using the core API and fmt/format.h (#1452_). For example, on macOS with clang the compile time of a test TU dropped from 2.3s to 0.3s with -O2 and from 0.6s to 0.3s with the default settings (-O0).

    Before (-O2)::

    % time c++ -c test.cc -I include -std=c++17 -O2 c++ -c test.cc -I include -std=c++17 -O2 2.22s user 0.08s system 99% cpu 2.311 total

    After (-O2)::

    % time c++ -c test.cc -I include -std=c++17 -O2 c++ -c test.cc -I include -std=c++17 -O2 0.26s user 0.04s system 98% cpu 0.303 total

    Before (default)::

    % time c++ -c test.cc -I include -std=c++17 c++ -c test.cc -I include -std=c++17 0.53s user 0.06s system 98% cpu 0.601 total

    After (default)::

    % time c++ -c test.cc -I include -std=c++17 c++ -c test.cc -I include -std=c++17 0.24s user 0.06s system 98% cpu 0.301 total

    It is still recommended to use fmt/core.h instead of fmt/format.h but the compile time difference is now smaller.

    Thanks @alex3d <https://github.com/alex3d>_ for the suggestion.

  • Named arguments are now stored on stack (no dynamic memory allocations) and the generated binary code is more compact and efficient. For example

    .. code:: c++

    #include <fmt/core.h>

    int main() { fmt::print("The answer is {answer}\n", fmt::arg("answer", 42)); }

    compiles to just (godbolt <https://godbolt.org/z/NcfEp_>__)

    .. code:: asm

    .LC0:
            .string "answer"
    .LC1:
            .string "The answer is {answer}\n"
    main:
            sub     rsp, 56
            mov     edi, OFFSET FLAT:.LC1
            mov     esi, 23
            movabs  rdx, 4611686018427387905
            lea     rax, [rsp+32]
            lea     rcx, [rsp+16]
            mov     QWORD PTR [rsp+8], 1
            mov     QWORD PTR [rsp], rax
            mov     DWORD PTR [rsp+16], 42
            mov     QWORD PTR [rsp+32], OFFSET FLAT:.LC0
            mov     DWORD PTR [rsp+40], 0
            call    fmt::v6::vprint(fmt::v6::basic_string_view<char>,
                                    fmt::v6::format_args)
            xor     eax, eax
            add     rsp, 56
            ret
    
        .L.str.1:
                .asciz  "answer"
    
  • Implemented compile-time checks for dynamic width and precision (#1614_):

    .. code:: c++

    #include <fmt/format.h>

    int main() { fmt::print(FMT_STRING("{0:{1}}"), 42); }

    now gives a compilation error because argument 1 doesn't exist::

    In file included from test.cc:1: include/fmt/format.h:2726:27: error: constexpr variable 'invalid_format' must be initialized by a constant expression FMT_CONSTEXPR_DECL bool invalid_format = ^ ... include/fmt/core.h:569:26: note: in call to '&checker(s, {}).context_->on_error(&"argument not found"[0])' if (id >= num_args_) on_error("argument not found"); ^

  • Added sentinel support to fmt::join (#1689_):

    .. code:: c++

    struct zstring_sentinel {}; bool operator==(const char* p, zstring_sentinel) { return p == '\0'; } bool operator!=(const char p, zstring_sentinel) { return *p != '\0'; }

    struct zstring { const char* p; const char* begin() const { return p; } zstring_sentinel end() const { return {}; } };

    auto s = fmt::format("{}", fmt::join(zstring{"hello"}, "_")); // s == "h_e_l_l_o"

    Thanks @BRevzin (Barry Revzin) <https://github.com/BRevzin>_.

  • Added support for named args, clear and reserve to dynamic_format_arg_store (#1655, #1663, #1674, #1677). Thanks @vsolontsov-ll (Vladimir Solontsov) <https://github.com/vsolontsov-ll>_.

  • Added support for the 'c' format specifier to integral types for compatibility with std::format (#1652_).

  • Implemented the 'L' format specifier for locale-specific formatting of floating-point numbers for compatibility with std::format (#1624_). The 'n' specifier is now disabled by default but can be enabled via the FMT_DEPRECATED_N_SPECIFIER macro.

  • The '=' format specifier is now disabled by default for compatibility with std::format. It can be enabled via the FMT_DEPRECATED_NUMERIC_ALIGN macro.

  • Optimized handling of small format strings. For example,

    .. code:: c++

    fmt::format("Result: {}: ({},{},{},{})", str1, str2, str3, str4, str5)
    

    is now ~40% faster (#1685_).

  • Improved compatibility between fmt::printf with the standard specs (#1595, #1682, #1683, #1687, #1699, #1717). Thanks @rimathia <https://github.com/rimathia>_.

  • Fixed handling of operator<<` overloads that use copyfmt`` (#1666_).

  • Removed the following deprecated APIs:

    • FMT_STRING_ALIAS and fmt macros - replaced by FMT_STRING
    • fmt::basic_string_view::char_type - replaced by fmt::basic_string_view::value_type
    • convert_to_int
    • format_arg_store::types
    • *parse_context - replaced by *format_parse_context
    • FMT_DEPRECATED_INCLUDE_OS
    • FMT_DEPRECATED_PERCENT - incompatible with std::format
    • *writer - replaced by compiled format API
  • Deprecated arg_formatter.

  • Renamed the internal namespace to detail (#1538_). The former is still provided as an alias if the FMT_USE_INTERNAL macro is defined.

  • Added the FMT_OS CMake option to control inclusion of OS-specific APIs in the fmt target. This can be useful for embedded platforms (#1654, #1656). Thanks @kwesolowski (Krzysztof Wesolowski) <https://github.com/kwesolowski>_.

  • Replaced FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION with the FMT_FUZZ macro to prevent interferring with fuzzing of projects using {fmt} (#1650). Thanks @asraa (Asra Ali) <https://github.com/asraa>.

  • Fixed compatibility with emscripten (#1736, #1737). Thanks @ArthurSonzogni (Arthur Sonzogni) <https://github.com/ArthurSonzogni>_.

  • Improved documentation (#704, #1643, #1660, #1681, #1691, #1706, #1714, #1721, #1739, #1740, #1741). Thanks @senior7515 (Alexander Gallego) <https://github.com/senior7515>, @lsr0 (Lindsay Roberts) <https://github.com/lsr0>, @puetzk (Kevin Puetz) <https://github.com/puetzk>, @fpelliccioni (Fernando Pelliccioni) <https://github.com/fpelliccioni>, Alexey Kuzmenko, @jelly (jelle van der Waa) <https://github.com/jelly>, @claremacrae (Clare Macrae) <https://github.com/claremacrae>, @jiapengwen (文佳鹏) <https://github.com/jiapengwen>, @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>_.

  • Implemented various build configuration fixes and improvements (#1603, #1657, #1702, #1728). Thanks @scramsby (Scott Ramsby) <https://github.com/scramsby>, @jtojnar (Jan Tojnar) <https://github.com/jtojnar>, @orivej (Orivej Desh) <https://github.com/orivej>, @flagarde <https://github.com/flagarde>.

  • Fixed various warnings and compilation issues (#1616, #1620, #1622, #1625, #1627, #1628, #1629, #1631, #1633, #1649, #1658, #1661, #1667, #1668, #1669, #1692, #1696, #1697, #1707, #1712, #1716, #1722, #1724, #1729, #1738, #1742, #1743, #1744, #1747, #1750). Thanks @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>, @gabime (Gabi Melman) <https://github.com/gabime>, @johnor (Johan) <https://github.com/johnor>, @gabime (Dmitry Kurkin) <https://github.com/Kurkin>, @invexed (James Beach) <https://github.com/invexed>, @peterbell10 <https://github.com/peterbell10>, @daixtrose (Markus Werle) <https://github.com/daixtrose>, @petrutlucian94 (Lucian Petrut) <https://github.com/petrutlucian94>, @Neargye (Daniil Goncharov) <https://github.com/Neargye>, @ambitslix (Attila M. Szilagyi) <https://github.com/ambitslix>, @gabime (Gabi Melman) <https://github.com/gabime>, @erthink (Leonid Yuriev) <https://github.com/erthink>, @tohammer (Tobias Hammer ) <https://github.com/tohammer>, @0x8000-0000 (Florin Iucha) <https://github.com/0x8000-0000>.

6.2.1 - 2020-05-09

  • Fixed ostream support in sprintf (#1631_).

  • Fixed type detection when using implicit conversion to string_view and ostream operator<< inconsistently (#1662_).

6.2.0 - 2020-04-05

  • Improved error reporting when trying to format an object of a non-formattable type:

    .. code:: c++

    fmt::format("{}", S());

    now gives::

    include/fmt/core.h:1015:5: error: static_assert failed due to requirement 'formattable' "Cannot format argument. To make type T formattable provide a formatter specialization: https://fmt.dev/latest/api.html#formatting-user-defined-types" static_assert( ^ ... note: in instantiation of function template specialization 'fmt::v6::format<char [3], S, char>' requested here fmt::format("{}", S()); ^

    if S is not formattable.

  • Reduced the library size by ~10%.

  • Always print decimal point if # is specified (#1476, #1498):

    .. code:: c++

    fmt::print("{:#.0f}", 42.0);

    now prints 42.

  • Implemented the 'L' specifier for locale-specific numeric formatting to improve compatibility with std::format. The 'n' specifier is now deprecated and will be removed in the next major release.

  • Moved OS-specific APIs such as windows_error from fmt/format.h to fmt/os.h. You can define FMT_DEPRECATED_INCLUDE_OS to automatically include fmt/os.h from fmt/format.h for compatibility but this will be disabled in the next major release.

  • Added precision overflow detection in floating-point formatting.

  • Implemented detection of invalid use of fmt::arg.

  • Used type_identity to block unnecessary template argument deduction. Thanks Tim Song.

  • Improved UTF-8 handling (#1109_):

    .. code:: c++

    fmt::print("┌{0:─^{2}}┐\n" "│{1: ^{2}}│\n" "└{0:─^{2}}┘\n", "", "Привет, мир!", 20);

    now prints::

    ┌────────────────────┐ │ Привет, мир! │ └────────────────────┘

    on systems that support Unicode.

  • Added experimental dynamic argument storage (#1170, #1584):

    .. code:: c++

    fmt::dynamic_format_arg_storefmt::format_context store; store.push_back("answer"); store.push_back(42); fmt::vprint("The {} is {}.\n", store);

    prints::

    The answer is 42.

    Thanks @vsolontsov-ll (Vladimir Solontsov) <https://github.com/vsolontsov-ll>_.

  • Made fmt::join accept initializer_list (#1591). Thanks @Rapotkinnik (Nikolay Rapotkin) <https://github.com/Rapotkinnik>.

  • Fixed handling of empty tuples (#1588_).

  • Fixed handling of output iterators in format_to_n (#1506_).

  • Fixed formatting of std::chrono::duration types to wide output (#1533). Thanks @zeffy (pilao) <https://github.com/zeffy>.

  • Added const begin and end overload to buffers (#1553). Thanks @dominicpoeschko <https://github.com/dominicpoeschko>.

  • Added the ability to disable floating-point formatting via FMT_USE_FLOAT, FMT_USE_DOUBLE and FMT_USE_LONG_DOUBLE macros for extremely memory-constrained embedded system (#1590). Thanks @albaguirre (Alberto Aguirre) <https://github.com/albaguirre>.

  • Made FMT_STRING work with constexpr string_view (#1589). Thanks @scramsby (Scott Ramsby) <https://github.com/scramsby>.

  • Implemented a minor optimization in the format string parser (#1560). Thanks @IkarusDeveloper <https://github.com/IkarusDeveloper>.

  • Improved attribute detection (#1469, #1475, #1576). Thanks @federico-busato (Federico) <https://github.com/federico-busato>, @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>, @refnum <https://github.com/refnum>.

  • Improved documentation (#1481, #1523). Thanks @JackBoosY (Jack·Boos·Yu) <https://github.com/JackBoosY>, @imba-tjd (谭九鼎) <https://github.com/imba-tjd>.

  • Fixed symbol visibility on Linux when compiling with -fvisibility=hidden (#1535). Thanks @milianw (Milian Wolff) <https://github.com/milianw>.

  • Implemented various build configuration fixes and improvements (#1264, #1460, #1534, #1536, #1545, #1546, #1566, #1582, #1597, #1598). Thanks @ambitslix (Attila M. Szilagyi) <https://github.com/ambitslix>, @jwillikers (Jordan Williams) <https://github.com/jwillikers>, @stac47 (Laurent Stacul) <https://github.com/stac47>_.

  • Fixed various warnings and compilation issues (#1433, #1461, #1470, #1480, #1485, #1492, #1493, #1504, #1505, #1512, #1515, #1516, #1518, #1519, #1520, #1521, #1522, #1524, #1530, #1531, #1532, #1539, #1547, #1548, #1554, #1567, #1568, #1569, #1571, #1573, #1575, #1581, #1583, #1586, #1587, #1594, #1596, #1604, #1606, #1607, #1609). Thanks @marti4d (Chris Martin) <https://github.com/marti4d>, @iPherian <https://github.com/iPherian>, @parkertomatoes <https://github.com/parkertomatoes>, @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>, @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>, @DanielaE (Daniela Engert) <https://github.com/DanielaE>, @torsten48 <https://github.com/torsten48>, @tohammer (Tobias Hammer) <https://github.com/tohammer>, @lefticus (Jason Turner) <https://github.com/lefticus>, @ryusakki (Haise) <https://github.com/ryusakki>, @adnsv (Alex Denisov) <https://github.com/adnsv>, @fghzxm <https://github.com/fghzxm>, @refnum <https://github.com/refnum>, @pramodk (Pramod Kumbhar) <https://github.com/pramodk>, @Spirrwell <https://github.com/Spirrwell>, @scramsby (Scott Ramsby) <https://github.com/scramsby>_.

6.1.2 - 2019-12-11

  • Fixed ABI compatibility with libfmt.so.6.0.0 (#1471_).

  • Fixed handling types convertible to std::string_view (#1451). Thanks @denizevrenci (Deniz Evrenci) <https://github.com/denizevrenci>.

  • Made CUDA test an opt-in enabled via the FMT_CUDA_TEST CMake option.

  • Fixed sign conversion warnings (#1440). Thanks @0x8000-0000 (Florin Iucha) <https://github.com/0x8000-0000>.

6.1.1 - 2019-12-04

  • Fixed shared library build on Windows (#1443, #1445, #1446, #1450). Thanks @egorpugin (Egor Pugin) <https://github.com/egorpugin>, @bbolli (Beat Bolli) <https://github.com/bbolli>.

  • Added a missing decimal point in exponent notation with trailing zeros.

  • Removed deprecated format_arg_store::TYPES.

6.1.0 - 2019-12-01

  • {fmt} now formats IEEE 754 float and double using the shortest decimal representation with correct rounding by default:

    .. code:: c++

    #include #include <fmt/core.h>

    int main() { fmt::print("{}", M_PI); }

    prints 3.141592653589793.

  • Made the fast binary to decimal floating-point formatter the default, simplified it and improved performance. {fmt} is now 15 times faster than libc++'s std::ostringstream, 11 times faster than printf and 10% faster than double-conversion on dtoa-benchmark <https://github.com/fmtlib/dtoa-benchmark>_:

    ================== ========= ======= Function Time (ns) Speedup ================== ========= ======= ostringstream 1,346.30 1.00x ostrstream 1,195.74 1.13x sprintf 995.08 1.35x doubleconv 99.10 13.59x fmt 88.34 15.24x ================== ========= =======

    .. image:: https://user-images.githubusercontent.com/576385/ 69767160-cdaca400-112f-11ea-9fc5-347c9f83caad.png

  • {fmt} no longer converts float arguments to double. In particular this improves the default (shortest) representation of floats and makes fmt::format consistent with std::format specs (#1336, #1353, #1360, #1361):

    .. code:: c++

    fmt::print("{}", 0.1f);

    prints 0.1 instead of 0.10000000149011612.

    Thanks @orivej (Orivej Desh) <https://github.com/orivej>_.

  • Made floating-point formatting output consistent with printf/iostreams (#1376, #1417).

  • Added support for 128-bit integers (#1287_):

    .. code:: c++

    fmt::print("{}", std::numeric_limits<__int128_t>::max());

    prints 170141183460469231731687303715884105727.

    Thanks @denizevrenci (Deniz Evrenci) <https://github.com/denizevrenci>_.

  • The overload of print that takes text_style is now atomic, i.e. the output from different threads doesn't interleave (#1351). Thanks @tankiJong (Tanki Zhang) <https://github.com/tankiJong>.

  • Made compile time in the header-only mode ~20% faster by reducing the number of template instantiations. wchar_t overload of vprint was moved from fmt/core.h to fmt/format.h.

  • Added an overload of fmt::join that works with tuples (#1322, #1330):

    .. code:: c++

    #include #include <fmt/ranges.h>

    int main() { std::tuple<char, int, float> t{'a', 1, 2.0f}; fmt::print("{}", t); }

    prints ('a', 1, 2.0).

    Thanks @jeremyong (Jeremy Ong) <https://github.com/jeremyong>_.

  • Changed formatting of octal zero with prefix from "00" to "0":

    .. code:: c++

    fmt::print("{:#o}", 0);

    prints 0.

  • The locale is now passed to ostream insertion (<<) operators (#1406_):

    .. code:: c++

    #include <fmt/locale.h> #include <fmt/ostream.h>

    struct S { double value; };

    std::ostream& operator<<(std::ostream& os, S s) { return os << s.value; }

    int main() { auto s = fmt::format(std::locale("fr_FR.UTF-8"), "{}", S{0.42}); // s == "0,42" }

    Thanks @dlaugt (Daniel Laügt) <https://github.com/dlaugt>_.

  • Locale-specific number formatting now uses grouping (#1393, #1394). Thanks @skrdaniel <https://github.com/skrdaniel>_.

  • Fixed handling of types with deleted implicit rvalue conversion to const char** (#1421_):

    .. code:: c++

    struct mystring { operator const char*() const&; operator const char*() &; operator const char*() const&& = delete; operator const char*() && = delete; }; mystring str; fmt::print("{}", str); // now compiles

  • Enums are now mapped to correct underlying types instead of int (#1286). Thanks @agmt (Egor Seredin) <https://github.com/agmt>.

  • Enum classes are no longer implicitly converted to int (#1424_).

  • Added basic_format_parse_context for consistency with C++20 std::format and deprecated basic_parse_context.

  • Fixed handling of UTF-8 in precision (#1389, #1390). Thanks @tajtiattila (Attila Tajti) <https://github.com/tajtiattila>_.

  • {fmt} can now be installed on Linux, macOS and Windows with Conda <https://docs.conda.io/en/latest/>__ using its conda-forge <https://conda-forge.org>__ package <https://github.com/conda-forge/fmt-feedstock>__ (#1410_)::

    conda install -c conda-forge fmt

    Thanks @tdegeus (Tom de Geus) <https://github.com/tdegeus>_.

  • Added a CUDA test (#1285, #1317). Thanks @luncliff (Park DongHa) <https://github.com/luncliff>_ and @risa2000 <https://github.com/risa2000>_.

  • Improved documentation (#1276, #1291, #1296, #1315, #1332, #1337, #1395_ #1418). Thanks @waywardmonkeys (Bruce Mitchener) <https://github.com/waywardmonkeys>, @pauldreik (Paul Dreik) <https://github.com/pauldreik>, @jackoalan (Jack Andersen) <https://github.com/jackoalan>.

  • Various code improvements (#1358, #1407). Thanks @orivej (Orivej Desh) <https://github.com/orivej>, @dpacbach (David P. Sicilia) <https://github.com/dpacbach>,

  • Fixed compile-time format string checks for user-defined types (#1292_).

  • Worked around a false positive in unsigned-integer-overflow sanitizer (#1377_).

  • Fixed various warnings and compilation issues (#1273, #1278, #1280, #1281, #1288, #1290, #1301, #1305, #1306, #1309, #1312, #1313, #1316, #1319, #1320, #1326, #1328, #1344, #1345, #1347, #1349, #1354, #1362, #1366, #1364, #1370, #1371, #1385, #1388, #1397, #1414, #1416, #1422_ #1427, #1431, #1433). Thanks @hhb <https://github.com/hhb>, @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>, @gabime (Gabi Melman) <https://github.com/gabime>, @neheb (Rosen Penev) <https://github.com/neheb>, @vedranmiletic (Vedran Miletić) <https://github.com/vedranmiletic>, @dkavolis (Daumantas Kavolis) <https://github.com/dkavolis>, @mwinterb <https://github.com/mwinterb>, @orivej (Orivej Desh) <https://github.com/orivej>, @denizevrenci (Deniz Evrenci) <https://github.com/denizevrenci> @leonklingele <https://github.com/leonklingele>, @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>, @kent-tri <https://github.com/kent-tri>, @0x8000-0000 (Florin Iucha) <https://github.com/0x8000-0000>, @marti4d (Chris Martin) <https://github.com/marti4d>_.

6.0.0 - 2019-08-26

  • Switched to the MIT license <https://github.com/fmtlib/fmt/blob/5a4b24613ba16cc689977c3b5bd8274a3ba1dd1f/LICENSE.rst>_ with an optional exception that allows distributing binary code without attribution.

  • Floating-point formatting is now locale-independent by default:

    .. code:: c++

    #include #include <fmt/core.h>

    int main() { std::locale::global(std::locale("ru_RU.UTF-8")); fmt::print("value = {}", 4.2); }

    prints "value = 4.2" regardless of the locale.

    For locale-specific formatting use the n specifier:

    .. code:: c++

    std::locale::global(std::locale("ru_RU.UTF-8")); fmt::print("value = {:n}", 4.2);

    prints "value = 4,2".

  • Added an experimental Grisu floating-point formatting algorithm implementation (disabled by default). To enable it compile with the FMT_USE_GRISU macro defined to 1:

    .. code:: c++

    #define FMT_USE_GRISU 1 #include <fmt/format.h>

    auto s = fmt::format("{}", 4.2); // formats 4.2 using Grisu

    With Grisu enabled, {fmt} is 13x faster than std::ostringstream (libc++) and 10x faster than sprintf on dtoa-benchmark <https://github.com/fmtlib/dtoa-benchmark>_ (full results <https://fmt.dev/unknown_mac64_clang10.0.html>_):

    .. image:: https://user-images.githubusercontent.com/576385/ 54883977-9fe8c000-4e28-11e9-8bde-272d122e7c52.jpg

  • Separated formatting and parsing contexts for consistency with C++20 std::format <http://eel.is/c++draft/format>_, removing the undocumented basic_format_context::parse_context() function.

  • Added oss-fuzz <https://github.com/google/oss-fuzz>_ support (#1199). Thanks @pauldreik (Paul Dreik) <https://github.com/pauldreik>.

  • formatter specializations now always take precedence over operator<< (#952_):

    .. code:: c++

    #include #include <fmt/ostream.h>

    struct S {};

    std::ostream& operator<<(std::ostream& os, S) { return os << 1; }

    template <> struct fmt::formatter : fmt::formatter { auto format(S, format_context& ctx) { return formatter::format(2, ctx); } };

    int main() { std::cout << S() << "\n"; // prints 1 using operator<< fmt::print("{}\n", S()); // prints 2 using formatter }

  • Introduced the experimental fmt::compile function that does format string compilation (#618, #1169, #1171_):

    .. code:: c++

    #include <fmt/compile.h>

    auto f = fmt::compile("{}"); std::string s = fmt::format(f, 42); // can be called multiple times to // format different values // s == "42"

    It moves the cost of parsing a format string outside of the format function which can be beneficial when identically formatting many objects of the same types. Thanks @stryku (Mateusz Janek) <https://github.com/stryku>_.

  • Added experimental % format specifier that formats floating-point values as percentages (#1060, #1069, #1071_):

    .. code:: c++

    auto s = fmt::format("{:.1%}", 0.42); // s == "42.0%"

    Thanks @gawain-bolton (Gawain Bolton) <https://github.com/gawain-bolton>_.

  • Implemented precision for floating-point durations (#1004, #1012):

    .. code:: c++

    auto s = fmt::format("{:.1}", std::chrono::duration(1.234)); // s == 1.2s

    Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • Implemented chrono format specifiers %Q and %q that give the value and the unit respectively (#1019_):

    .. code:: c++

    auto value = fmt::format("{:%Q}", 42s); // value == "42" auto unit = fmt::format("{:%q}", 42s); // unit == "s"

    Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • Fixed handling of dynamic width in chrono formatter:

    .. code:: c++

    auto s = fmt::format("{0:{1}%H:%M:%S}", std::chrono::seconds(12345), 12); // ^ width argument index ^ width // s == "03:25:45 "

    Thanks Howard Hinnant.

  • Removed deprecated fmt/time.h. Use fmt/chrono.h instead.

  • Added fmt::format and fmt::vformat overloads that take text_style (#993, #994):

    .. code:: c++

    #include <fmt/color.h>

    std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red), "The answer is {}.", 42);

    Thanks @Naios (Denis Blank) <https://github.com/Naios>_.

  • Removed the deprecated color API (print_colored). Use the new API, namely print overloads that take text_style instead.

  • Made std::unique_ptr and std::shared_ptr formattable as pointers via fmt::ptr (#1121_):

    .. code:: c++

    std::unique_ptr p = ...; fmt::print("{}", fmt::ptr(p)); // prints p as a pointer

    Thanks @sighingnow (Tao He) <https://github.com/sighingnow>_.

  • Made print and vprint report I/O errors (#1098, #1099). Thanks @BillyDonahue (Billy Donahue) <https://github.com/BillyDonahue>_.

  • Marked deprecated APIs with the [[deprecated]] attribute and removed internal uses of deprecated APIs (#1022). Thanks @eliaskosunen (Elias Kosunen) <https://github.com/eliaskosunen>.

  • Modernized the codebase using more C++11 features and removing workarounds. Most importantly, buffer_context is now an alias template, so use buffer_context<T> instead of buffer_context<T>::type. These features require GCC 4.8 or later.

  • formatter specializations now always take precedence over implicit conversions to int and the undocumented convert_to_int trait is now deprecated.

  • Moved the undocumented basic_writer, writer, and wwriter types to the internal namespace.

  • Removed deprecated basic_format_context::begin(). Use out() instead.

  • Disallowed passing the result of join as an lvalue to prevent misuse.

  • Refactored the undocumented structs that represent parsed format specifiers to simplify the API and allow multibyte fill.

  • Moved SFINAE to template parameters to reduce symbol sizes.

  • Switched to fputws for writing wide strings so that it's no longer required to call _setmode on Windows (#1229, #1243). Thanks @jackoalan (Jack Andersen) <https://github.com/jackoalan>_.

  • Improved literal-based API (#1254). Thanks @sylveon (Charles Milette) <https://github.com/sylveon>.

  • Added support for exotic platforms without uintptr_t such as IBM i (AS/400) which has 128-bit pointers and only 64-bit integers (#1059_).

  • Added Sublime Text syntax highlighting config <https://github.com/fmtlib/fmt/blob/master/support/C%2B%2B.sublime-syntax>_ (#1037). Thanks @Kronuz (Germán Méndez Bravo) <https://github.com/Kronuz>.

  • Added the FMT_ENFORCE_COMPILE_STRING macro to enforce the use of compile-time format strings (#1231). Thanks @jackoalan (Jack Andersen) <https://github.com/jackoalan>.

  • Stopped setting CMAKE_BUILD_TYPE if {fmt} is a subproject (#1081_).

  • Various build improvements (#1039, #1078, #1091, #1103, #1177). Thanks @luncliff (Park DongHa) <https://github.com/luncliff>, @jasonszang (Jason Shuo Zang) <https://github.com/jasonszang>, @olafhering (Olaf Hering) <https://github.com/olafhering>, @Lecetem <https://github.com/Lectem>, @pauldreik (Paul Dreik) <https://github.com/pauldreik>.

  • Improved documentation (#1049, #1051, #1083, #1113, #1114, #1146, #1180, #1250, #1252, #1265). Thanks @mikelui (Michael Lui) <https://github.com/mikelui>, @foonathan (Jonathan Müller) <https://github.com/foonathan>, @BillyDonahue (Billy Donahue) <https://github.com/BillyDonahue>, @jwakely (Jonathan Wakely) <https://github.com/jwakely>, @kaisbe (Kais Ben Salah) <https://github.com/kaisbe>, @sdebionne (Samuel Debionne) <https://github.com/sdebionne>.

  • Fixed ambiguous formatter specialization in fmt/ranges.h (#1123_).

  • Fixed formatting of a non-empty std::filesystem::path which is an infinitely deep range of its components (#1268_).

  • Fixed handling of general output iterators when formatting characters (#1056, #1058). Thanks @abolz (Alexander Bolz) <https://github.com/abolz>_.

  • Fixed handling of output iterators in formatter specialization for ranges (#1064_).

  • Fixed handling of exotic character types (#1188_).

  • Made chrono formatting work with exceptions disabled (#1062_).

  • Fixed DLL visibility issues (#1134, #1147). Thanks @denchat <https://github.com/denchat>_.

  • Disabled the use of UDL template extension on GCC 9 (#1148_).

  • Removed misplaced format compile-time checks from printf (#1173_).

  • Fixed issues in the experimental floating-point formatter (#1072, #1129, #1153, #1155, #1210, #1222). Thanks @alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>_.

  • Fixed bugs discovered by fuzzing or during fuzzing integration (#1124, #1127, #1132, #1135, #1136, #1141, #1142, #1178, #1179, #1194). Thanks @pauldreik (Paul Dreik) <https://github.com/pauldreik>_.

  • Fixed building tests on FreeBSD and Hurd (#1043). Thanks @jackyf (Eugene V. Lyubimkin) <https://github.com/jackyf>.

  • Fixed various warnings and compilation issues (#998, #1006, #1008, #1011, #1025, #1027, #1028, #1029, #1030, #1031, #1054, #1063, #1068, #1074, #1075, #1079, #1086, #1088, #1089, #1094, #1101, #1102, #1105, #1107, #1115, #1117, #1118, #1120, #1123, #1139, #1140, #1143, #1144, #1150, #1151, #1152, #1154, #1156, #1159, #1175, #1181, #1186, #1187, #1191, #1197, #1200, #1203, #1205, #1206, #1213, #1214, #1217, #1228, #1230, #1232, #1235, #1236, #1240). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>, @mwinterb <https://github.com/mwinterb>, @eliaskosunen (Elias Kosunen) <https://github.com/eliaskosunen>, @morinmorin <https://github.com/morinmorin>, @ricco19 (Brian Ricciardelli) <https://github.com/ricco19>, @waywardmonkeys (Bruce Mitchener) <https://github.com/waywardmonkeys>, @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>, @remyabel <https://github.com/remyabel>, @pauldreik (Paul Dreik) <https://github.com/pauldreik>, @gsjaardema (Greg Sjaardema) <https://github.com/gsjaardema>, @rcane (Ronny Krüger) <https://github.com/rcane>, @mocabe <https://github.com/mocabe>, @denchat <https://github.com/denchat>, @cjdb (Christopher Di Bella) <https://github.com/cjdb>, @HazardyKnusperkeks (Björn Schäpers) <https://github.com/HazardyKnusperkeks>, @vedranmiletic (Vedran Miletić) <https://github.com/vedranmiletic>, @jackoalan (Jack Andersen) <https://github.com/jackoalan>, @DaanDeMeyer (Daan De Meyer) <https://github.com/DaanDeMeyer>, @starkmapper (Mark Stapper) <https://github.com/starkmapper>_.

5.3.0 - 2018-12-28

  • Introduced experimental chrono formatting support:

    .. code:: c++

    #include <fmt/chrono.h>

    int main() { using namespace std::literals::chrono_literals; fmt::print("Default format: {} {}\n", 42s, 100ms); fmt::print("strftime-like format: {:%H:%M:%S}\n", 3h + 15min + 30s); }

    prints::

    Default format: 42s 100ms strftime-like format: 03:15:30

  • Added experimental support for emphasis (bold, italic, underline, strikethrough), colored output to a file stream, and improved colored formatting API (#961, #967, #973_):

    .. code:: c++

    #include <fmt/color.h>

    int main() { print(fg(fmt::color::crimson) | fmt::emphasis::bold, "Hello, {}!\n", "world"); print(fg(fmt::color::floral_white) | bg(fmt::color::slate_gray) | fmt::emphasis::underline, "Hello, {}!\n", "мир"); print(fg(fmt::color::steel_blue) | fmt::emphasis::italic, "Hello, {}!\n", "世界"); }

    prints the following on modern terminals with RGB color support:

    .. image:: https://user-images.githubusercontent.com/576385/ 50405788-b66e7500-076e-11e9-9592-7324d1f951d8.png

    Thanks @Rakete1111 (Nicolas) <https://github.com/Rakete1111>_.

  • Added support for 4-bit terminal colors (#968, #974)

    .. code:: c++

    #include <fmt/color.h>

    int main() { print(fg(fmt::terminal_color::red), "stop\n"); }

    Note that these colors vary by terminal:

    .. image:: https://user-images.githubusercontent.com/576385/ 50405925-dbfc7e00-0770-11e9-9b85-333fab0af9ac.png

    Thanks @Rakete1111 (Nicolas) <https://github.com/Rakete1111>_.

  • Parameterized formatting functions on the type of the format string (#880, #881, #883, #885, #897, #920). Any object of type S that has an overloaded to_string_view(const S&) returning fmt::string_view can be used as a format string:

    .. code:: c++

    namespace my_ns { inline string_view to_string_view(const my_string& s) { return {s.data(), s.length()}; } }

    std::string message = fmt::format(my_string("The answer is {}."), 42);

    Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • Made std::string_view work as a format string (#898_):

    .. code:: c++

    auto message = fmt::format(std::string_view("The answer is {}."), 42);

    Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • Added wide string support to compile-time format string checks (#924_):

    .. code:: c++

    print(fmt(L"{:f}"), 42); // compile-time error: invalid type specifier

    Thanks @XZiar <https://github.com/XZiar>_.

  • Made colored print functions work with wide strings (#867_):

    .. code:: c++

    #include <fmt/color.h>

    int main() { print(fg(fmt::color::red), L"{}\n", 42); }

    Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • Introduced experimental Unicode support (#628, #891):

    .. code:: c++

    using namespace fmt::literals; auto s = fmt::format("{:*^5}"_u, "🤡"_u); // s == "🤡"_u

  • Improved locale support:

    .. code:: c++

    #include <fmt/locale.h>

    struct numpunct : std::numpunct { protected: char do_thousands_sep() const override { return '~'; } };

    std::locale loc; auto s = fmt::format(std::locale(loc, new numpunct()), "{:n}", 1234567); // s == "1~234~567"

  • Constrained formatting functions on proper iterator types (#921). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>.

  • Added make_printf_args and make_wprintf_args functions (#934). Thanks @tnovotny <https://github.com/tnovotny>.

  • Deprecated fmt::visit, parse_context, and wparse_context. Use fmt::visit_format_arg, format_parse_context, and wformat_parse_context instead.

  • Removed undocumented basic_fixed_buffer which has been superseded by the iterator-based API (#873, #902). Thanks @superfunc (hollywood programmer) <https://github.com/superfunc>_.

  • Disallowed repeated leading zeros in an argument ID:

    .. code:: c++

    fmt::print("{000}", 42); // error

  • Reintroduced support for gcc 4.4.

  • Fixed compilation on platforms with exotic double (#878_).

  • Improved documentation (#164, #877, #901, #906, #979). Thanks @kookjr (Mathew Cucuzella) <https://github.com/kookjr>, @DarkDimius (Dmitry Petrashko) <https://github.com/DarkDimius>, @HecticSerenity <https://github.com/HecticSerenity>.

  • Added pkgconfig support which makes it easier to consume the library from meson and other build systems (#916). Thanks @colemickens (Cole Mickens) <https://github.com/colemickens>.

  • Various build improvements (#909, #926, #937, #953, #959). Thanks @tchaikov (Kefu Chai) <https://github.com/tchaikov>, @luncliff (Park DongHa) <https://github.com/luncliff>, @AndreasSchoenle (Andreas Schönle) <https://github.com/AndreasSchoenle>, @hotwatermorning <https://github.com/hotwatermorning>, @Zefz (JohanJansen) <https://github.com/Zefz>.

  • Improved string_view construction performance (#914). Thanks @gabime (Gabi Melman) <https://github.com/gabime>.

  • Fixed non-matching char types (#895). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>.

  • Fixed format_to_n with std::back_insert_iterator (#913). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>.

  • Fixed locale-dependent formatting (#905_).

  • Fixed various compiler warnings and errors (#882, #886, #933, #941, #931, #943, #954, #956, #962, #965, #977, #983, #989). Thanks @Luthaf (Guillaume Fraux) <https://github.com/Luthaf>, @stevenhoving (Steven Hoving) <https://github.com/stevenhoving>, @christinaa (Kristina Brooks) <https://github.com/christinaa>, @lgritz (Larry Gritz) <https://github.com/lgritz>, @DanielaE (Daniela Engert) <https://github.com/DanielaE>, @0x8000-0000 (Sign Bit) <https://github.com/0x8000-0000>, @liuping1997 <https://github.com/liuping1997>.

5.2.1 - 2018-09-21

  • Fixed visit lookup issues on gcc 7 & 8 (#870). Thanks @medithe <https://github.com/medithe>.

  • Fixed linkage errors on older gcc.

  • Prevented fmt/range.h from specializing fmt::basic_string_view (#865, #868). Thanks @hhggit (dual) <https://github.com/hhggit>_.

  • Improved error message when formatting unknown types (#872). Thanks @foonathan (Jonathan Müller) <https://github.com/foonathan>,

  • Disabled templated user-defined literals when compiled under nvcc (#875). Thanks @CandyGumdrop (Candy Gumdrop) <https://github.com/CandyGumdrop>,

  • Fixed format_to formatting to wmemory_buffer (#874_).

5.2.0 - 2018-09-13

  • Optimized format string parsing and argument processing which resulted in up to 5x speed up on long format strings and significant performance boost on various benchmarks. For example, version 5.2 is 2.22x faster than 5.1 on decimal integer formatting with format_to (macOS, clang-902.0.39.2):

    ================== ======= ======= Method Time, s Speedup ================== ======= ======= fmt::format 5.1 0.58 fmt::format 5.2 0.35 1.66x fmt::format_to 5.1 0.51 fmt::format_to 5.2 0.23 2.22x sprintf 0.71 std::to_string 1.01 std::stringstream 1.73 ================== ======= =======

  • Changed the fmt macro from opt-out to opt-in to prevent name collisions. To enable it define the FMT_STRING_ALIAS macro to 1 before including fmt/format.h:

    .. code:: c++

    #define FMT_STRING_ALIAS 1 #include <fmt/format.h> std::string answer = format(fmt("{}"), 42);

  • Added compile-time format string checks to format_to overload that takes fmt::memory_buffer (#783_):

    .. code:: c++

    fmt::memory_buffer buf; // Compile-time error: invalid type specifier. fmt::format_to(buf, fmt("{:d}"), "foo");

  • Moved experimental color support to fmt/color.h and enabled the new API by default. The old API can be enabled by defining the FMT_DEPRECATED_COLORS macro.

  • Added formatting support for types explicitly convertible to fmt::string_view:

    .. code:: c++

    struct foo { explicit operator fmt::string_view() const { return "foo"; } }; auto s = format("{}", foo());

    In particular, this makes formatting function work with folly::StringPiece.

  • Implemented preliminary support for char*_t by replacing the format function overloads with a single function template parameterized on the string type.

  • Added support for dynamic argument lists (#814, #819). Thanks @MikePopoloski (Michael Popoloski) <https://github.com/MikePopoloski>_.

  • Reduced executable size overhead for embedded targets using newlib nano by making locale dependency optional (#839). Thanks @teajay-fr (Thomas Benard) <https://github.com/teajay-fr>.

  • Keep noexcept specifier when exceptions are disabled (#801, #810). Thanks @qis (Alexej Harm) <https://github.com/qis>_.

  • Fixed formatting of user-defined types providing operator<< with format_to_n (#806). Thanks @mkurdej (Marek Kurdej) <https://github.com/mkurdej>.

  • Fixed dynamic linkage of new symbols (#808_).

  • Fixed global initialization issue (#807_):

    .. code:: c++

    // This works on compilers with constexpr support. static const std::string answer = fmt::format("{}", 42);

  • Fixed various compiler warnings and errors (#804, #809, #811, #822, #827, #830, #838, #843, #844, #851, #852, #854). Thanks @henryiii (Henry Schreiner) <https://github.com/henryiii>, @medithe <https://github.com/medithe>, and @eliasdaler (Elias Daler) <https://github.com/eliasdaler>_.

5.1.0 - 2018-07-05

  • Added experimental support for RGB color output enabled with the FMT_EXTENDED_COLORS macro:

    .. code:: c++

    #define FMT_EXTENDED_COLORS #define FMT_HEADER_ONLY // or compile fmt with FMT_EXTENDED_COLORS defined #include <fmt/format.h>

    fmt::print(fmt::color::steel_blue, "Some beautiful text");

    The old API (the print_colored and vprint_colored functions and the color enum) is now deprecated. (#762_ #767). thanks @Remotion (Remo) <https://github.com/Remotion>.

  • Added quotes to strings in ranges and tuples (#766). Thanks @Remotion (Remo) <https://github.com/Remotion>.

  • Made format_to work with basic_memory_buffer (#776_).

  • Added vformat_to_n and wchar_t overload of format_to_n (#764, #769).

  • Made is_range and is_tuple_like part of public (experimental) API to allow specialization for user-defined types (#751, #759). Thanks @drrlvn (Dror Levin) <https://github.com/drrlvn>_.

  • Added more compilers to continuous integration and increased FMT_PEDANTIC warning levels (#736). Thanks @eliaskosunen (Elias Kosunen) <https://github.com/eliaskosunen>.

  • Fixed compilation with MSVC 2013.

  • Fixed handling of user-defined types in format_to (#793_).

  • Forced linking of inline vformat functions into the library (#795_).

  • Fixed incorrect call to on_align in '{:}=' (#750_).

  • Fixed floating-point formatting to a non-back_insert_iterator with sign & numeric alignment specified (#756_).

  • Fixed formatting to an array with format_to_n (#778_).

  • Fixed formatting of more than 15 named arguments (#754_).

  • Fixed handling of compile-time strings when including fmt/ostream.h. (#768_).

  • Fixed various compiler warnings and errors (#742, #748, #752, #770, #775, #779, #780, #790, #792, #800). Thanks @Remotion (Remo) <https://github.com/Remotion>, @gabime (Gabi Melman) <https://github.com/gabime>, @foonathan (Jonathan Müller) <https://github.com/foonathan>, @Dark-Passenger (Dhruv Paranjape) <https://github.com/Dark-Passenger>, and @0x8000-0000 (Sign Bit) <https://github.com/0x8000-0000>_.

5.0.0 - 2018-05-21

  • Added a requirement for partial C++11 support, most importantly variadic templates and type traits, and dropped FMT_VARIADIC_* emulation macros. Variadic templates are available since GCC 4.4, Clang 2.9 and MSVC 18.0 (2013). For older compilers use {fmt} version 4.x <https://github.com/fmtlib/fmt/releases/tag/4.1.0>_ which continues to be maintained and works with C++98 compilers.

  • Renamed symbols to follow standard C++ naming conventions and proposed a subset of the library for standardization in P0645R2 Text Formatting <https://wg21.link/P0645>_.

  • Implemented constexpr parsing of format strings and compile-time format string checks <https://fmt.dev/dev/api.html#compile-time-format-string-checks>_. For example

    .. code:: c++

    #include <fmt/format.h>

    std::string s = format(fmt("{:d}"), "foo");

    gives a compile-time error because d is an invalid specifier for strings (godbolt <https://godbolt.org/g/rnCy9Q>__)::

    ... :4:19: note: in instantiation of function template specialization 'fmt::v5::format<S, char [4]>' requested here std::string s = format(fmt("{:d}"), "foo"); ^ format.h:1337:13: note: non-constexpr function 'on_error' cannot be used in a constant expression handler.on_error("invalid type specifier");

    Compile-time checks require relaxed constexpr (C++14 feature) support. If the latter is not available, checks will be performed at runtime.

  • Separated format string parsing and formatting in the extension API to enable compile-time format string processing. For example

    .. code:: c++

    struct Answer {};

    namespace fmt { template <> struct formatter { constexpr auto parse(parse_context& ctx) { auto it = ctx.begin(); spec = *it; if (spec != 'd' && spec != 's') throw format_error("invalid specifier"); return ++it; }

     template <typename FormatContext>
     auto format(Answer, FormatContext& ctx) {
       return spec == 's' ?
         format_to(ctx.begin(), "{}", "fourty-two") :
         format_to(ctx.begin(), "{}", 42);
     }
    
     char spec = 0;
    

    }; }

    std::string s = format(fmt("{:x}"), Answer());

    gives a compile-time error due to invalid format specifier (godbolt <https://godbolt.org/g/2jQ1Dv>__)::

    ... :12:45: error: expression '' is not a constant expression throw format_error("invalid specifier");

  • Added iterator support <https://fmt.dev/dev/api.html#output-iterator-support>_:

    .. code:: c++

    #include #include <fmt/format.h>

    std::vector out; fmt::format_to(std::back_inserter(out), "{}", 42);

  • Added the format_to_n <https://fmt.dev/dev/api.html#_CPPv2N3fmt11format_to_nE8OutputItNSt6size_tE11string_viewDpRK4Args>_ function that restricts the output to the specified number of characters (#298_):

    .. code:: c++

    char out[4]; fmt::format_to_n(out, sizeof(out), "{}", 12345); // out == "1234" (without terminating '\0')

  • Added the formatted_size <https://fmt.dev/dev/api.html#_CPPv2N3fmt14formatted_sizeE11string_viewDpRK4Args>_ function for computing the output size:

    .. code:: c++

    #include <fmt/format.h>

    auto size = fmt::formatted_size("{}", 12345); // size == 5

  • Improved compile times by reducing dependencies on standard headers and providing a lightweight core API <https://fmt.dev/dev/api.html#core-api>_:

    .. code:: c++

    #include <fmt/core.h>

    fmt::print("The answer is {}.", 42);

    See Compile time and code bloat <https://github.com/fmtlib/fmt#compile-time-and-code-bloat>_.

  • Added the make_format_args <https://fmt.dev/dev/api.html#_CPPv2N3fmt16make_format_argsEDpRK4Args>_ function for capturing formatting arguments:

    .. code:: c++

    // Prints formatted error message. void vreport_error(const char *format, fmt::format_args args) { fmt::print("Error: "); fmt::vprint(format, args); } template <typename... Args> void report_error(const char *format, const Args & ... args) { vreport_error(format, fmt::make_format_args(args...)); }

  • Added the make_printf_args function for capturing printf arguments (#687, #694). Thanks @Kronuz (Germán Méndez Bravo) <https://github.com/Kronuz>_.

  • Added prefix v to non-variadic functions taking format_args to distinguish them from variadic ones:

    .. code:: c++

    std::string vformat(string_view format_str, format_args args);

    template <typename... Args> std::string format(string_view format_str, const Args & ... args);

  • Added experimental support for formatting ranges, containers and tuple-like types in fmt/ranges.h (#735_):

    .. code:: c++

    #include <fmt/ranges.h>

    std::vector v = {1, 2, 3}; fmt::print("{}", v); // prints {1, 2, 3}

    Thanks @Remotion (Remo) <https://github.com/Remotion>_.

  • Implemented wchar_t date and time formatting (#712_):

    .. code:: c++

    #include <fmt/time.h>

    std::time_t t = std::time(nullptr); auto s = fmt::format(L"The date is {:%Y-%m-%d}.", *std::localtime(&t));

    Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>_.

  • Provided more wide string overloads (#724). Thanks @DanielaE (Daniela Engert) <https://github.com/DanielaE>.

  • Switched from a custom null-terminated string view class to string_view in the format API and provided fmt::string_view which implements a subset of std::string_view API for pre-C++17 systems.

  • Added support for std::experimental::string_view (#607_):

    .. code:: c++

    #include <fmt/core.h> #include <experimental/string_view>

    fmt::print("{}", std::experimental::string_view("foo"));

    Thanks @virgiliofornazin (Virgilio Alexandre Fornazin) <https://github.com/virgiliofornazin>__.

  • Allowed mixing named and automatic arguments:

    .. code:: c++

    fmt::format("{} {two}", 1, fmt::arg("two", 2));

  • Removed the write API in favor of the format API <https://fmt.dev/dev/api.html#format-api>_ with compile-time handling of format strings.

  • Disallowed formatting of multibyte strings into a wide character target (#606_).

  • Improved documentation (#515, #614, #617, #661, #680). Thanks @ibell (Ian Bell) <https://github.com/ibell>, @mihaitodor (Mihai Todor) <https://github.com/mihaitodor>, and @johnthagen <https://github.com/johnthagen>.

  • Implemented more efficient handling of large number of format arguments.

  • Introduced an inline namespace for symbol versioning.

  • Added debug postfix d to the fmt library name (#636_).

  • Removed unnecessary fmt/ prefix in includes (#397). Thanks @chronoxor (Ivan Shynkarenka) <https://github.com/chronoxor>.

  • Moved fmt/*.h to include/fmt/*.h to prevent irrelevant files and directories appearing on the include search paths when fmt is used as a subproject and moved source files to the src directory.

  • Added qmake project file support/fmt.pro (#641). Thanks @cowo78 (Giuseppe Corbelli) <https://github.com/cowo78>.

  • Added Gradle build file support/build.gradle (#649). Thanks @luncliff (Park DongHa) <https://github.com/luncliff>.

  • Removed FMT_CPPFORMAT CMake option.

  • Fixed a name conflict with the macro CHAR_WIDTH in glibc (#616). Thanks @aroig (Abdó Roig-Maranges) <https://github.com/aroig>.

  • Fixed handling of nested braces in fmt::join (#638_).

  • Added SOURCELINK_SUFFIX for compatibility with Sphinx 1.5 (#497). Thanks @ginggs (Graham Inggs) <https://github.com/ginggs>.

  • Added a missing inline in the header-only mode (#626). Thanks @aroig (Abdó Roig-Maranges) <https://github.com/aroig>.

  • Fixed various compiler warnings (#640, #656, #679, #681, #705__, #715, #717, #720, #723, #726, #730, #739). Thanks @peterbell10 <https://github.com/peterbell10>, @LarsGullik <https://github.com/LarsGullik>, @foonathan (Jonathan Müller) <https://github.com/foonathan>, @eliaskosunen (Elias Kosunen) <https://github.com/eliaskosunen>, @christianparpart (Christian Parpart) <https://github.com/christianparpart>, @DanielaE (Daniela Engert) <https://github.com/DanielaE>, and @mwinterb <https://github.com/mwinterb>.

  • Worked around an MSVC bug and fixed several warnings (#653). Thanks @alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>.

  • Worked around GCC bug 67371 (#682_).

  • Fixed compilation with -fno-exceptions (#655). Thanks @chenxiaolong (Andrew Gunnerson) <https://github.com/chenxiaolong>.

  • Made constexpr remove_prefix gcc version check tighter (#648_).

  • Renamed internal type enum constants to prevent collision with poorly written C libraries (#644_).

  • Added detection of wostream operator<< (#650_).

  • Fixed compilation on OpenBSD (#660). Thanks @hubslave <https://github.com/hubslave>.

  • Fixed compilation on FreeBSD 12 (#732). Thanks @dankm <https://github.com/dankm>.

  • Fixed compilation when there is a mismatch between -std options between the library and user code (#664_).

  • Fixed compilation with GCC 7 and -std=c++11 (#734_).

  • Improved generated binary code on GCC 7 and older (#668_).

  • Fixed handling of numeric alignment with no width (#675_).

  • Fixed handling of empty strings in UTF8/16 converters (#676). Thanks @vgalka-sl (Vasili Galka) <https://github.com/vgalka-sl>.

  • Fixed formatting of an empty string_view (#689_).

  • Fixed detection of string_view on libc++ (#686_).

  • Fixed DLL issues (#696). Thanks @sebkoenig <https://github.com/sebkoenig>.

  • Fixed compile checks for mixing narrow and wide strings (#690_).

  • Disabled unsafe implicit conversion to std::string (#729_).

  • Fixed handling of reused format specs (as in fmt::join) for pointers (#725). Thanks @mwinterb <https://github.com/mwinterb>.

  • Fixed installation of fmt/ranges.h (#738). Thanks @sv1990 <https://github.com/sv1990>.

4.1.0 - 2017-12-20

  • Added fmt::to_wstring() in addition to fmt::to_string() (#559). Thanks @alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>.

  • Added support for C++17 std::string_view (#571_ and #578). Thanks @thelostt (Mário Feroldi) <https://github.com/thelostt> and @mwinterb <https://github.com/mwinterb>_.

  • Enabled stream exceptions to catch errors (#581). Thanks @crusader-mike <https://github.com/crusader-mike>.

  • Allowed formatting of class hierarchies with fmt::format_arg() (#547). Thanks @rollbear (Björn Fahller) <https://github.com/rollbear>.

  • Removed limitations on character types (#563). Thanks @Yelnats321 (Elnar Dakeshov) <https://github.com/Yelnats321>.

  • Conditionally enabled use of std::allocator_traits (#583). Thanks @mwinterb <https://github.com/mwinterb>.

  • Added support for const variadic member function emulation with FMT_VARIADIC_CONST (#591). Thanks @ludekvodicka (Ludek Vodicka) <https://github.com/ludekvodicka>.

  • Various bugfixes: bad overflow check, unsupported implicit type conversion when determining formatting function, test segfaults (#551), ill-formed macros (#542) and ambiguous overloads (#580). Thanks @xylosper (Byoung-young Lee) <https://github.com/xylosper>.

  • Prevented warnings on MSVC (#605, #602, and #545), clang (#582), GCC (#573), various conversion warnings (#609, #567, #553 and #553), and added override and [[noreturn]] (#549 and #555). Thanks @alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>, @virgiliofornazin (Virgilio Alexandre Fornazin) <https://gihtub.com/virgiliofornazin>, @alexanderbock (Alexander Bock) <https://github.com/alexanderbock>, @yumetodo <https://github.com/yumetodo>, @VaderY (Császár Mátyás) <https://github.com/VaderY>, @jpcima (JP Cimalando) <https://github.com/jpcima>, @thelostt (Mário Feroldi) <https://github.com/thelostt>, and @Manu343726 (Manu Sánchez) <https://github.com/Manu343726>_.

  • Improved CMake: Used GNUInstallDirs to set installation location (#610) and fixed warnings (#536 and #556). Thanks @mikecrowe (Mike Crowe) <https://github.com/mikecrowe>, @evgen231 <https://github.com/evgen231>_ and @henryiii (Henry Schreiner) <https://github.com/henryiii>_.

4.0.0 - 2017-06-27

  • Removed old compatibility headers cppformat/*.h and CMake options (#527). Thanks @maddinat0r (Alex Martin) <https://github.com/maddinat0r>.

  • Added string.h containing fmt::to_string() as alternative to std::to_string() as well as other string writer functionality (#326_ and #441_):

    .. code:: c++

    #include "fmt/string.h"

    std::string answer = fmt::to_string(42);

    Thanks to @glebov-andrey (Andrey Glebov) <https://github.com/glebov-andrey>_.

  • Moved fmt::printf() to new printf.h header and allowed %s as generic specifier (#453), made %.f more conformant to regular printf() (#490), added custom writer support (#476) and implemented missing custom argument formatting (#339 and #340_):

    .. code:: c++

    #include "fmt/printf.h"

    // %s format specifier can be used with any argument type. fmt::printf("%s", 42);

    Thanks @mojoBrendan <https://github.com/mojoBrendan>, @manylegged (Arthur Danskin) <https://github.com/manylegged> and @spacemoose (Glen Stark) <https://github.com/spacemoose>. See also #360, #335_ and #331_.

  • Added container.h containing a BasicContainerWriter to write to containers like std::vector (#450). Thanks @polyvertex (Jean-Charles Lefebvre) <https://github.com/polyvertex>.

  • Added fmt::join() function that takes a range and formats its elements separated by a given string (#466_):

    .. code:: c++

    #include "fmt/format.h"

    std::vector v = {1.2, 3.4, 5.6}; // Prints "(+01.20, +03.40, +05.60)". fmt::print("({:+06.2f})", fmt::join(v.begin(), v.end(), ", "));

    Thanks @olivier80 <https://github.com/olivier80>_.

  • Added support for custom formatting specifications to simplify customization of built-in formatting (#444). Thanks @polyvertex (Jean-Charles Lefebvre) <https://github.com/polyvertex>. See also #439_.

  • Added fmt::format_system_error() for error code formatting (#323_ and #526). Thanks @maddinat0r (Alex Martin) <https://github.com/maddinat0r>.

  • Added thread-safe fmt::localtime() and fmt::gmtime() as replacement for the standard version to time.h (#396). Thanks @codicodi <https://github.com/codicodi>.

  • Internal improvements to NamedArg and ArgLists (#389_ and #390). Thanks @chronoxor <https://github.com/chronoxor>.

  • Fixed crash due to bug in FormatBuf (#493). Thanks @effzeh <https://github.com/effzeh>. See also #480_ and #491_.

  • Fixed handling of wide strings in fmt::StringWriter.

  • Improved compiler error messages (#357_).

  • Fixed various warnings and issues with various compilers (#494, #499, #483, #485, #482, #475, #473_ and #414). Thanks @chronoxor <https://github.com/chronoxor>, @zhaohuaxishi <https://github.com/zhaohuaxishi>, @pkestene (Pierre Kestener) <https://github.com/pkestene>, @dschmidt (Dominik Schmidt) <https://github.com/dschmidt>_ and @0x414c (Alexey Gorishny) <https://github.com/0x414c>_ .

  • Improved CMake: targets are now namespaced (#511_ and #513), added support for header-only printf.h (#354), fixed issue with minimal supported library subset (#418, #419 and #420). Thanks @bjoernthiel (Bjoern Thiel) <https://github.com/bjoernthiel>, @niosHD (Mario Werner) <https://github.com/niosHD>, @LogicalKnight (Sean LK) <https://github.com/LogicalKnight> and @alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>_.

  • Improved documentation. Thanks to @pwm1234 (Phil) <https://github.com/pwm1234>_ for #393_.

3.0.2 - 2017-06-14

  • Added FMT_VERSION macro (#411_).

  • Used FMT_NULL instead of literal 0 (#409). Thanks @alabuzhev (Alex Alabuzhev) <https://github.com/alabuzhev>.

  • Added extern templates for format_float (#413_).

  • Fixed implicit conversion issue (#507_).

  • Fixed signbit detection (#423_).

  • Fixed naming collision (#425_).

  • Fixed missing intrinsic for C++/CLI (#457). Thanks @calumr (Calum Robinson) <https://github.com/calumr>

  • Fixed Android detection (#458). Thanks @Gachapen (Magnus Bjerke Vik) <https://github.com/Gachapen>.

  • Use lean windows.h if not in header-only mode (#503). Thanks @Quentin01 (Quentin Buathier) <https://github.com/Quentin01>.

  • Fixed issue with CMake exporting C++11 flag (#445). Thanks @EricWF (Eric) <https://github.com/EricWF>.

  • Fixed issue with nvcc and MSVC compiler bug and MinGW (#505_).

  • Fixed DLL issues (#469_ and #502). Thanks @richardeakin (Richard Eakin) <https://github.com/richardeakin> and @AndreasSchoenle (Andreas Schönle) <https://github.com/AndreasSchoenle>_.

  • Fixed test compilation under FreeBSD (#433_).

  • Fixed various warnings (#403, #410 and #510). Thanks @Lecetem <https://github.com/Lectem>, @chenhayat (Chen Hayat) <https://github.com/chenhayat>_ and @trozen <https://github.com/trozen>_.

  • Worked around a broken __builtin_clz in clang with MS codegen (#519_).

  • Removed redundant include (#479_).

  • Fixed documentation issues.

3.0.1 - 2016-11-01

  • Fixed handling of thousands separator (#353_).

  • Fixed handling of unsigned char strings (#373_).

  • Corrected buffer growth when formatting time (#367_).

  • Removed warnings under MSVC and clang (#318, #250, also merged #385_ and #361). Thanks @jcelerier (Jean-Michaël Celerier) <https://github.com/jcelerier> and @nmoehrle (Nils Moehrle) <https://github.com/nmoehrle>_.

  • Fixed compilation issues under Android (#327, #345 and #381), FreeBSD (#358), Cygwin (#388), MinGW (#355) as well as other issues (#350, #366, #348, #402, #405). Thanks to @dpantele (Dmitry) <https://github.com/dpantele>, @hghwng (Hugh Wang) <https://github.com/hghwng>, @arvedarved (Tilman Keskinöz) <https://github.com/arvedarved>, @LogicalKnight (Sean) <https://github.com/LogicalKnight>_ and @JanHellwig (Jan Hellwig) <https://github.com/janhellwig>_.

  • Fixed some documentation issues and extended specification (#320, #333, #347, #362). Thanks to @smellman (Taro Matsuzawa aka. btm) <https://github.com/smellman>_.

3.0.0 - 2016-05-07

  • The project has been renamed from C++ Format (cppformat) to fmt for consistency with the used namespace and macro prefix (#307_). Library headers are now located in the fmt directory:

    .. code:: c++

    #include "fmt/format.h"

    Including format.h from the cppformat directory is deprecated but works via a proxy header which will be removed in the next major version.

    The documentation is now available at https://fmt.dev.

  • Added support for strftime <http://en.cppreference.com/w/cpp/chrono/c/strftime>-like date and time formatting <https://fmt.dev/3.0.0/api.html#date-and-time-formatting> (#283_):

    .. code:: c++

    #include "fmt/time.h"

    std::time_t t = std::time(nullptr); // Prints "The date is 2016-04-29." (with the current date) fmt::print("The date is {:%Y-%m-%d}.", *std::localtime(&t));

  • std::ostream support including formatting of user-defined types that provide overloaded operator<< has been moved to fmt/ostream.h:

    .. code:: c++

    #include "fmt/ostream.h"

    class Date { int year_, month_, day_; public: Date(int year, int month, int day) : year_(year), month_(month), day_(day) {}

    friend std::ostream &operator<<(std::ostream &os, const Date &d) {
      return os << d.year_ << '-' << d.month_ << '-' << d.day_;
    }
    

    };

    std::string s = fmt::format("The date is {}", Date(2012, 12, 9)); // s == "The date is 2012-12-9"

  • Added support for custom argument formatters <https://fmt.dev/3.0.0/api.html#argument-formatters>_ (#235_).

  • Added support for locale-specific integer formatting with the n specifier (#305_):

    .. code:: c++

    std::setlocale(LC_ALL, "en_US.utf8"); fmt::print("cppformat: {:n}\n", 1234567); // prints 1,234,567

  • Sign is now preserved when formatting an integer with an incorrect printf format specifier (#265_):

    .. code:: c++

    fmt::printf("%lld", -42); // prints -42

    Note that it would be an undefined behavior in std::printf.

  • Length modifiers such as ll are now optional in printf formatting functions and the correct type is determined automatically (#255_):

    .. code:: c++

    fmt::printf("%d", std::numeric_limits::max());

    Note that it would be an undefined behavior in std::printf.

  • Added initial support for custom formatters (#231_).

  • Fixed detection of user-defined literal support on Intel C++ compiler (#311, #312). Thanks to @dean0x7d (Dean Moldovan) <https://github.com/dean0x7d>_ and @speth (Ray Speth) <https://github.com/speth>_.

  • Reduced compile time (#243, #249, #317_):

    .. image:: https://cloud.githubusercontent.com/assets/4831417/11614060/ b9e826d2-9c36-11e5-8666-d4131bf503ef.png

    .. image:: https://cloud.githubusercontent.com/assets/4831417/11614080/ 6ac903cc-9c37-11e5-8165-26df6efae364.png

    Thanks to @dean0x7d (Dean Moldovan) <https://github.com/dean0x7d>_.

  • Compile test fixes (#313). Thanks to @dean0x7d (Dean Moldovan) <https://github.com/dean0x7d>.

  • Documentation fixes (#239, #248, #252, #258, #260, #301, #309). Thanks to @ReadmeCritic <https://github.com/ReadmeCritic> @Gachapen (Magnus Bjerke Vik) <https://github.com/Gachapen>_ and @jwilk (Jakub Wilk) <https://github.com/jwilk>_.

  • Fixed compiler and sanitizer warnings (#244, #256, #259, #263, #274, #277, #286, #291, #296, #308) Thanks to @mwinterb <https://github.com/mwinterb>, @pweiskircher (Patrik Weiskircher) <https://github.com/pweiskircher>, @Naios <https://github.com/Naios>_.

  • Improved compatibility with Windows Store apps (#280, #285). Thanks to @mwinterb <https://github.com/mwinterb>_.

  • Added tests of compatibility with older C++ standards (#273). Thanks to @niosHD <https://github.com/niosHD>.

  • Fixed Android build (#271). Thanks to @newnon <https://github.com/newnon>.

  • Changed ArgMap to be backed by a vector instead of a map. (#261, #262). Thanks to @mwinterb <https://github.com/mwinterb>_.

  • Added fprintf overload that writes to a std::ostream (#251). Thanks to nickhutchinson (Nicholas Hutchinson) <https://github.com/nickhutchinson>.

  • Export symbols when building a Windows DLL (#245). Thanks to macdems (Maciek Dems) <https://github.com/macdems>.

  • Fixed compilation on Cygwin (#304_).

  • Implemented a workaround for a bug in Apple LLVM version 4.2 of clang (#276_).

  • Implemented a workaround for Google Test bug #705 <https://github.com/google/googletest/issues/705>_ on gcc 6 (#268). Thanks to octoploid <https://github.com/octoploid>.

  • Removed Biicode support because the latter has been discontinued.

2.1.1 - 2016-04-11

  • The install location for generated CMake files is now configurable via the FMT_CMAKE_DIR CMake variable (#299). Thanks to @niosHD <https://github.com/niosHD>.

  • Documentation fixes (#252_).

2.1.0 - 2016-03-21

  • Project layout and build system improvements (#267_):

    • The code have been moved to the cppformat directory. Including format.h from the top-level directory is deprecated but works via a proxy header which will be removed in the next major version.

    • C++ Format CMake targets now have proper interface definitions.

    • Installed version of the library now supports the header-only configuration.

    • Targets doc, install, and test are now disabled if C++ Format is included as a CMake subproject. They can be enabled by setting FMT_DOC, FMT_INSTALL, and FMT_TEST in the parent project.

    Thanks to @niosHD <https://github.com/niosHD>_.

2.0.1 - 2016-03-13

  • Improved CMake find and package support (#264). Thanks to @niosHD <https://github.com/niosHD>.

  • Fix compile error with Android NDK and mingw32 (#241). Thanks to @Gachapen (Magnus Bjerke Vik) <https://github.com/Gachapen>.

  • Documentation fixes (#248, #260).

2.0.0 - 2015-12-01

General


* [Breaking] Named arguments (`#169`_, `#173`_, `#174`_):

  .. code:: c++

    fmt::print("The answer is {answer}.", fmt::arg("answer", 42));

  Thanks to `@jamboree <https://github.com/jamboree>`_.

* [Experimental] User-defined literals for format and named arguments
  (`#204`_, `#206`_, `#207`_):

  .. code:: c++

    using namespace fmt::literals;
    fmt::print("The answer is {answer}.", "answer"_a=42);

  Thanks to `@dean0x7d (Dean Moldovan) <https://github.com/dean0x7d>`_.

* [Breaking] Formatting of more than 16 arguments is now supported when using
  variadic templates (`#141`_).
  Thanks to `@Shauren <https://github.com/Shauren>`_.

* Runtime width specification (`#168`_):

  .. code:: c++

    fmt::format("{0:{1}}", 42, 5); // gives "   42"

  Thanks to `@jamboree <https://github.com/jamboree>`_.

* [Breaking] Enums are now formatted with an overloaded ``std::ostream``
  insertion operator (``operator<<``) if available (`#232`_).

* [Breaking] Changed default ``bool`` format to textual, "true" or "false"
  (`#170`_):

  .. code:: c++
  
    fmt::print("{}", true); // prints "true"

  To print ``bool`` as a number use numeric format specifier such as ``d``:

  .. code:: c++

    fmt::print("{:d}", true); // prints "1"

* ``fmt::printf`` and ``fmt::sprintf`` now support formatting of ``bool`` with
  the ``%s`` specifier giving textual output, "true" or "false" (`#223`_):

  .. code:: c++

    fmt::printf("%s", true); // prints "true"

  Thanks to `@LarsGullik <https://github.com/LarsGullik>`_.

* [Breaking] ``signed char`` and ``unsigned char`` are now formatted as integers
  by default (`#217`_).

* [Breaking] Pointers to C strings can now be formatted with the ``p`` specifier
  (`#223`_):

  .. code:: c++

    fmt::print("{:p}", "test"); // prints pointer value

  Thanks to `@LarsGullik <https://github.com/LarsGullik>`_.

* [Breaking] ``fmt::printf`` and ``fmt::sprintf`` now print null pointers as
  ``(nil)`` and null strings as ``(null)`` for consistency with glibc (`#226`_).
  Thanks to `@LarsGullik <https://github.com/LarsGullik>`_.

* [Breaking] ``fmt::(s)printf`` now supports formatting of objects of
  user-defined types that provide an overloaded ``std::ostream`` insertion
  operator (``operator<<``) (`#201`_):

  .. code:: c++

    fmt::printf("The date is %s", Date(2012, 12, 9));

* [Breaking] The ``Buffer`` template is now part of the public API and can be
  used to implement custom memory buffers (`#140`_). Thanks to
  `@polyvertex (Jean-Charles Lefebvre) <https://github.com/polyvertex>`_.

* [Breaking] Improved compatibility between ``BasicStringRef`` and
  `std::experimental::basic_string_view
  <http://en.cppreference.com/w/cpp/experimental/basic_string_view>`_
  (`#100`_, `#159`_, `#183`_):

  - Comparison operators now compare string content, not pointers
  - ``BasicStringRef::c_str`` replaced by ``BasicStringRef::data``
  - ``BasicStringRef`` is no longer assumed to be null-terminated

  References to null-terminated strings are now represented by a new class,
  ``BasicCStringRef``.

* Dependency on pthreads introduced by Google Test is now optional (`#185`_).

* New CMake options ``FMT_DOC``, ``FMT_INSTALL`` and ``FMT_TEST`` to control
  generation of ``doc``, ``install`` and ``test`` targets respectively, on by
  default (`#197`_, `#198`_, `#200`_).
  Thanks to `@maddinat0r (Alex Martin) <https://github.com/maddinat0r>`_.

* ``noexcept`` is now used when compiling with MSVC2015 (`#215`_).
  Thanks to `@dmkrepo (Dmitriy) <https://github.com/dmkrepo>`_.

* Added an option to disable use of ``windows.h`` when ``FMT_USE_WINDOWS_H``
  is defined as 0 before including ``format.h`` (`#171`_).
  Thanks to `@alfps (Alf P. Steinbach) <https://github.com/alfps>`_.

* [Breaking] ``windows.h`` is now included with ``NOMINMAX`` unless
  ``FMT_WIN_MINMAX`` is defined. This is done to prevent breaking code using
  ``std::min`` and ``std::max`` and only affects the header-only configuration
  (`#152`_, `#153`_, `#154`_).
  Thanks to `@DevO2012 <https://github.com/DevO2012>`_.

* Improved support for custom character types (`#171`_).
  Thanks to `@alfps (Alf P. Steinbach) <https://github.com/alfps>`_.

* Added an option to disable use of IOStreams when ``FMT_USE_IOSTREAMS``
  is defined as 0 before including ``format.h`` (`#205`_, `#208`_).
  Thanks to `@JodiTheTigger <https://github.com/JodiTheTigger>`_.

* Improved detection of ``isnan``, ``isinf`` and ``signbit``.

Optimization
  • Made formatting of user-defined types more efficient with a custom stream buffer (#92, #230). Thanks to @NotImplemented <https://github.com/NotImplemented>_.

  • Further improved performance of fmt::Writer on integer formatting and fixed a minor regression. Now it is ~7% faster than karma::generate on Karma's benchmark (#186_).

  • [Breaking] Reduced compiled code size <https://github.com/fmtlib/fmt#compile-time-and-code-bloat>_ (#143, #149).

Distribution


* [Breaking] Headers are now installed in
  ``${CMAKE_INSTALL_PREFIX}/include/cppformat`` (`#178`_).
  Thanks to `@jackyf (Eugene V. Lyubimkin) <https://github.com/jackyf>`_.

* [Breaking] Changed the library name from ``format`` to ``cppformat``
  for consistency with the project name and to avoid potential conflicts
  (`#178`_).
  Thanks to `@jackyf (Eugene V. Lyubimkin) <https://github.com/jackyf>`_.

* C++ Format is now available in `Debian <https://www.debian.org/>`_ GNU/Linux
  (`stretch <https://packages.debian.org/source/stretch/cppformat>`_,
  `sid <https://packages.debian.org/source/sid/cppformat>`_) and 
  derived distributions such as
  `Ubuntu <https://launchpad.net/ubuntu/+source/cppformat>`_ 15.10 and later
  (`#155`_)::

    $ sudo apt-get install libcppformat1-dev

  Thanks to `@jackyf (Eugene V. Lyubimkin) <https://github.com/jackyf>`_.

* `Packages for Fedora and RHEL
  <https://admin.fedoraproject.org/pkgdb/package/cppformat/>`_ are now
  available. Thanks to Dave Johansen.
  
* C++ Format can now be installed via `Homebrew <http://brew.sh/>`_ on OS X
  (`#157`_)::

    $ brew install cppformat

  Thanks to `@ortho <https://github.com/ortho>`_, Anatoliy Bulukin.

Documentation
  • Migrated from ReadTheDocs to GitHub Pages for better responsiveness and reliability (#128_). New documentation address is http://cppformat.github.io/.

  • Added Building the documentation <https://fmt.dev/2.0.0/usage.html#building-the-documentation>_ section to the documentation.

  • Documentation build script is now compatible with Python 3 and newer pip versions (#189, #209). Thanks to @JodiTheTigger <https://github.com/JodiTheTigger>_ and @xentec <https://github.com/xentec>_.

  • Documentation fixes and improvements (#36, #75, #125, #160, #161, #162, #165, #210). Thanks to @syohex (Syohei YOSHIDA) <https://github.com/syohex>_ and bug reporters.

  • Fixed out-of-tree documentation build (#177). Thanks to @jackyf (Eugene V. Lyubimkin) <https://github.com/jackyf>.

Fixes


* Fixed ``initializer_list`` detection (`#136`_).
  Thanks to `@Gachapen (Magnus Bjerke Vik) <https://github.com/Gachapen>`_.

* [Breaking] Fixed formatting of enums with numeric format specifiers in
  ``fmt::(s)printf`` (`#131`_, `#139`_):

  .. code:: c++

    enum { ANSWER = 42 };
    fmt::printf("%d", ANSWER);

  Thanks to `@Naios <https://github.com/Naios>`_.

* Improved compatibility with old versions of MinGW
  (`#129`_, `#130`_, `#132`_).
  Thanks to `@cstamford (Christopher Stamford) <https://github.com/cstamford>`_.

* Fixed a compile error on MSVC with disabled exceptions (`#144`_).

* Added a workaround for broken implementation of variadic templates in MSVC2012
  (`#148`_).

* Placed the anonymous namespace within ``fmt`` namespace for the header-only
  configuration (`#171`_).
  Thanks to `@alfps (Alf P. Steinbach) <https://github.com/alfps>`_.

* Fixed issues reported by Coverity Scan (`#187`_, `#192`_).

* Implemented a workaround for a name lookup bug in MSVC2010 (`#188`_).

* Fixed compiler warnings (`#95`_, `#96`_, `#114`_, `#135`_, `#142`_, `#145`_,
  `#146`_, `#158`_, `#163`_, `#175`_, `#190`_, `#191`_, `#194`_, `#196`_,
  `#216`_, `#218`_, `#220`_, `#229`_, `#233`_, `#234`_, `#236`_, `#281`_,
  `#289`_). Thanks to
  `@seanmiddleditch (Sean Middleditch) <https://github.com/seanmiddleditch>`_,
  `@dixlorenz (Dix Lorenz) <https://github.com/dixlorenz>`_,
  `@CarterLi (李通洲) <https://github.com/CarterLi>`_,
  `@Naios <https://github.com/Naios>`_,
  `@fmatthew5876 (Matthew Fioravante) <https://github.com/fmatthew5876>`_,
  `@LevskiWeng (Levski Weng) <https://github.com/LevskiWeng>`_,
  `@rpopescu <https://github.com/rpopescu>`_,
  `@gabime (Gabi Melman) <https://github.com/gabime>`_,
  `@cubicool (Jeremy Moles) <https://github.com/cubicool>`_,
  `@jkflying (Julian Kent) <https://github.com/jkflying>`_,
  `@LogicalKnight (Sean L) <https://github.com/LogicalKnight>`_,
  `@inguin (Ingo van Lil) <https://github.com/inguin>`_ and
  `@Jopie64 (Johan) <https://github.com/Jopie64>`_.

* Fixed portability issues (mostly causing test failures) on ARM, ppc64,
  ppc64le, s390x and SunOS 5.11 i386 (`#138`_, `#179`_, `#180`_, `#202`_,
  `#225`_, `Red Hat Bugzilla Bug 1260297
  <https://bugzilla.redhat.com/show_bug.cgi?id=1260297>`_).
  Thanks to `@Naios <https://github.com/Naios>`_,
  `@jackyf (Eugene V. Lyubimkin) <https://github.com/jackyf>`_ and
  Dave Johansen.

* Fixed a name conflict with macro ``free`` defined in ``crtdbg.h`` when
  ``_CRTDBG_MAP_ALLOC`` is set (`#211`_).

* Fixed shared library build on OS X (`#212`_).
  Thanks to `@dean0x7d (Dean Moldovan) <https://github.com/dean0x7d>`_.

* Fixed an overload conflict on MSVC when ``/Zc:wchar_t-`` option is specified
  (`#214`_).
  Thanks to `@slavanap (Vyacheslav Napadovsky) <https://github.com/slavanap>`_.

* Improved compatibility with MSVC 2008 (`#236`_).
  Thanks to `@Jopie64 (Johan) <https://github.com/Jopie64>`_.

* Improved compatibility with bcc32 (`#227`_).

* Fixed ``static_assert`` detection on Clang (`#228`_).
  Thanks to `@dean0x7d (Dean Moldovan) <https://github.com/dean0x7d>`_.

1.1.0 - 2015-03-06
------------------

* Added ``BasicArrayWriter``, a class template that provides operations for
  formatting and writing data into a fixed-size array
  (`#105`_ and `#122`_):

  .. code:: c++
  
    char buffer[100];
    fmt::ArrayWriter w(buffer);
    w.write("The answer is {}", 42);

* Added `0 A.D. <http://play0ad.com/>`_ and `PenUltima Online (POL)
  <http://www.polserver.com/>`_ to the list of notable projects using C++ Format.

* C++ Format now uses MSVC intrinsics for better formatting performance
  (`#115`_, `#116`_, `#118`_ and `#121`_).
  Previously these optimizations where only used on GCC and Clang.
  Thanks to `@CarterLi <https://github.com/CarterLi>`_ and
  `@objectx <https://github.com/objectx>`_.

* CMake install target (`#119`_).
  Thanks to `@TrentHouliston <https://github.com/TrentHouliston>`_.

  You can now install C++ Format with ``make install`` command.

* Improved `Biicode <http://www.biicode.com/>`_ support
  (`#98`_ and `#104`_). Thanks to
  `@MariadeAnton <https://github.com/MariadeAnton>`_ and
  `@franramirez688 <https://github.com/franramirez688>`_.

* Improved support for building with `Android NDK
  <https://developer.android.com/tools/sdk/ndk/index.html>`_ (`#107`_).
  Thanks to `@newnon <https://github.com/newnon>`_.
  
  The `android-ndk-example <https://github.com/fmtlib/android-ndk-example>`_
  repository provides and example of using C++ Format with Android NDK:

  .. image:: https://raw.githubusercontent.com/fmtlib/android-ndk-example/
            master/screenshot.png

* Improved documentation of ``SystemError`` and ``WindowsError`` (`#54`_).

* Various code improvements (`#110`_, `#111`_ `#112`_).
  Thanks to `@CarterLi <https://github.com/CarterLi>`_.

* Improved compile-time errors when formatting wide into narrow strings
  (`#117`_).

* Fixed ``BasicWriter::write`` without formatting arguments when C++11 support
  is disabled (`#109`_).

* Fixed header-only build on OS X with GCC 4.9 (`#124`_).

* Fixed packaging issues (`#94`_).

* Added `changelog <https://github.com/fmtlib/fmt/blob/master/ChangeLog.rst>`_
  (`#103`_).

1.0.0 - 2015-02-05
------------------

* Add support for a header-only configuration when ``FMT_HEADER_ONLY`` is
  defined before including ``format.h``:

  .. code:: c++

    #define FMT_HEADER_ONLY
    #include "format.h"

* Compute string length in the constructor of ``BasicStringRef``
  instead of the ``size`` method
  (`#79`_).
  This eliminates size computation for string literals on reasonable optimizing
  compilers.

* Fix formatting of types with overloaded ``operator <<`` for ``std::wostream``
  (`#86`_):

  .. code:: c++

    fmt::format(L"The date is {0}", Date(2012, 12, 9));

* Fix linkage of tests on Arch Linux (`#89`_).

* Allow precision specifier for non-float arguments (`#90`_):

  .. code:: c++

    fmt::print("{:.3}\n", "Carpet"); // prints "Car"

* Fix build on Android NDK (`#93`_)

* Improvements to documentation build procedure.

* Remove ``FMT_SHARED`` CMake variable in favor of standard `BUILD_SHARED_LIBS
  <http://www.cmake.org/cmake/help/v3.0/variable/BUILD_SHARED_LIBS.html>`_.

* Fix error handling in ``fmt::fprintf``.

* Fix a number of warnings.

0.12.0 - 2014-10-25
-------------------

* [Breaking] Improved separation between formatting and buffer management.
  ``Writer`` is now a base class that cannot be instantiated directly.
  The new ``MemoryWriter`` class implements the default buffer management
  with small allocations done on stack. So ``fmt::Writer`` should be replaced
  with ``fmt::MemoryWriter`` in variable declarations.

  Old code:

  .. code:: c++

    fmt::Writer w;

  New code: 

  .. code:: c++

    fmt::MemoryWriter w;

  If you pass ``fmt::Writer`` by reference, you can continue to do so:

  .. code:: c++

      void f(fmt::Writer &w);

  This doesn't affect the formatting API.

* Support for custom memory allocators (`#69`_)

* Formatting functions now accept `signed char` and `unsigned char` strings as
  arguments (`#73`_):

  .. code:: c++

    auto s = format("GLSL version: {}", glGetString(GL_VERSION));

* Reduced code bloat. According to the new `benchmark results
  <https://github.com/fmtlib/fmt#compile-time-and-code-bloat>`_,
  cppformat is close to ``printf`` and by the order of magnitude better than
  Boost Format in terms of compiled code size.

* Improved appearance of the documentation on mobile by using the `Sphinx
  Bootstrap theme <http://ryan-roemer.github.io/sphinx-bootstrap-theme/>`_:

  .. |old| image:: https://cloud.githubusercontent.com/assets/576385/4792130/
                   cd256436-5de3-11e4-9a62-c077d0c2b003.png

  .. |new| image:: https://cloud.githubusercontent.com/assets/576385/4792131/
                   cd29896c-5de3-11e4-8f59-cac952942bf0.png
  
  +-------+-------+
  |  Old  |  New  |
  +-------+-------+
  | |old| | |new| |
  +-------+-------+

0.11.0 - 2014-08-21
-------------------

* Safe printf implementation with a POSIX extension for positional arguments:

  .. code:: c++

    fmt::printf("Elapsed time: %.2f seconds", 1.23);
    fmt::printf("%1$s, %3$d %2$s", weekday, month, day);

* Arguments of ``char`` type can now be formatted as integers (`#55`_):

  .. code:: c++

    fmt::format("0x{0:02X}", 'a');

* Deprecated parts of the API removed.

* The library is now built and tested on MinGW with Appveyor in addition to
  existing test platforms Linux/GCC, OS X/Clang, Windows/MSVC.

0.10.0 - 2014-07-01
-------------------

**Improved API**

* All formatting methods are now implemented as variadic functions instead
  of using ``operator<<`` for feeding arbitrary arguments into a temporary
  formatter object. This works both with C++11 where variadic templates are
  used and with older standards where variadic functions are emulated by
  providing lightweight wrapper functions defined with the ``FMT_VARIADIC``
  macro. You can use this macro for defining your own portable variadic
  functions:

  .. code:: c++

    void report_error(const char *format, const fmt::ArgList &args) {
      fmt::print("Error: {}");
      fmt::print(format, args);
    }
    FMT_VARIADIC(void, report_error, const char *)

    report_error("file not found: {}", path);

  Apart from a more natural syntax, this also improves performance as there
  is no need to construct temporary formatter objects and control arguments'
  lifetimes. Because the wrapper functions are very lightweight, this doesn't
  cause code bloat even in pre-C++11 mode.

* Simplified common case of formatting an ``std::string``. Now it requires a
  single function call:

  .. code:: c++

    std::string s = format("The answer is {}.", 42);

  Previously it required 2 function calls:

  .. code:: c++

    std::string s = str(Format("The answer is {}.") << 42);

  Instead of unsafe ``c_str`` function, ``fmt::Writer`` should be used directly
  to bypass creation of ``std::string``:

  .. code:: c++

    fmt::Writer w;
    w.write("The answer is {}.", 42);
    w.c_str();  // returns a C string

  This doesn't do dynamic memory allocation for small strings and is less error
  prone as the lifetime of the string is the same as for ``std::string::c_str``
  which is well understood (hopefully).

* Improved consistency in naming functions that are a part of the public API.
  Now all public functions are lowercase following the standard library
  conventions. Previously it was a combination of lowercase and
  CapitalizedWords.
  Issue `#50`_.

* Old functions are marked as deprecated and will be removed in the next
  release.

**Other Changes**

* Experimental support for printf format specifications (work in progress):

  .. code:: c++

    fmt::printf("The answer is %d.", 42);
    std::string s = fmt::sprintf("Look, a %s!", "string");

* Support for hexadecimal floating point format specifiers ``a`` and ``A``:

  .. code:: c++

    print("{:a}", -42.0); // Prints -0x1.5p+5
    print("{:A}", -42.0); // Prints -0X1.5P+5

* CMake option ``FMT_SHARED`` that specifies whether to build format as a
  shared library (off by default).

0.9.0 - 2014-05-13
------------------

* More efficient implementation of variadic formatting functions.

* ``Writer::Format`` now has a variadic overload:

  .. code:: c++

    Writer out;
    out.Format("Look, I'm {}!", "variadic");

* For efficiency and consistency with other overloads, variadic overload of
  the ``Format`` function now returns ``Writer`` instead of ``std::string``.
  Use the ``str`` function to convert it to ``std::string``:

  .. code:: c++

    std::string s = str(Format("Look, I'm {}!", "variadic"));

* Replaced formatter actions with output sinks: ``NoAction`` -> ``NullSink``,
  ``Write`` -> ``FileSink``, ``ColorWriter`` -> ``ANSITerminalSink``.
  This improves naming consistency and shouldn't affect client code unless
  these classes are used directly which should be rarely needed.

* Added ``ThrowSystemError`` function that formats a message and throws
  ``SystemError`` containing the formatted message and system-specific error
  description. For example, the following code

  .. code:: c++

    FILE *f = fopen(filename, "r");
    if (!f)
      ThrowSystemError(errno, "Failed to open file '{}'") << filename;

  will throw ``SystemError`` exception with description
  "Failed to open file '<filename>': No such file or directory" if file
  doesn't exist.

* Support for AppVeyor continuous integration platform.

* ``Format`` now throws ``SystemError`` in case of I/O errors.

* Improve test infrastructure. Print functions are now tested by redirecting
  the output to a pipe.

0.8.0 - 2014-04-14
------------------

* Initial release