diff --git a/test/src/unit-to_chars.cpp b/test/src/unit-to_chars.cpp new file mode 100644 index 00000000..c9b326d9 --- /dev/null +++ b/test/src/unit-to_chars.cpp @@ -0,0 +1,469 @@ +/* + __ _____ _____ _____ + __| | __| | | | JSON for Modern C++ (test suite) +| | |__ | | | | | | version 3.0.1 +|_____|_____|_____|_|___| https://github.com/nlohmann/json + +Licensed under the MIT License . +Copyright (c) 2013-2017 Niels Lohmann . + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. +*/ + +// XXX: +// Only compile these tests if 'float' and 'double' are IEEE-754 single- and +// double-precision numbers, resp. + +#include "catch.hpp" + +#include "json.hpp" +using nlohmann::detail::dtoa_impl::reinterpret_bits; + +static float make_float(uint32_t sign_bit, uint32_t biased_exponent, uint32_t significand) +{ + assert(sign_bit == 0 || sign_bit == 1); + assert(biased_exponent <= 0xFF); + assert(significand <= 0x007FFFFF); + + uint32_t bits = 0; + + bits |= sign_bit << 31; + bits |= biased_exponent << 23; + bits |= significand; + + return reinterpret_bits(bits); +} + +// ldexp -- convert f * 2^e to IEEE single precision +static float make_float(uint64_t f, int e) +{ + constexpr uint64_t kHiddenBit = 0x00800000; + constexpr uint64_t kSignificandMask = 0x007FFFFF; + constexpr int kPhysicalSignificandSize = 23; // Excludes the hidden bit. + constexpr int kExponentBias = 0x7F + kPhysicalSignificandSize; + constexpr int kDenormalExponent = 1 - kExponentBias; + constexpr int kMaxExponent = 0xFF - kExponentBias; + + while (f > kHiddenBit + kSignificandMask) { + f >>= 1; + e++; + } + if (e >= kMaxExponent) { + return std::numeric_limits::infinity(); + } + if (e < kDenormalExponent) { + return 0.0; + } + while (e > kDenormalExponent && (f & kHiddenBit) == 0) { + f <<= 1; + e--; + } + + uint64_t biased_exponent; + if (e == kDenormalExponent && (f & kHiddenBit) == 0) + biased_exponent = 0; + else + biased_exponent = static_cast(e + kExponentBias); + + uint64_t bits = (f & kSignificandMask) | (biased_exponent << kPhysicalSignificandSize); + return reinterpret_bits(static_cast(bits)); +} + +static double make_double(uint64_t sign_bit, uint64_t biased_exponent, uint64_t significand) +{ + assert(sign_bit == 0 || sign_bit == 1); + assert(biased_exponent <= 0x7FF); + assert(significand <= 0x000FFFFFFFFFFFFF); + + uint64_t bits = 0; + + bits |= sign_bit << 63; + bits |= biased_exponent << 52; + bits |= significand; + + return reinterpret_bits(bits); +} + +// ldexp -- convert f * 2^e to IEEE double precision +static double make_double(uint64_t f, int e) +{ + constexpr uint64_t kHiddenBit = 0x0010000000000000; + constexpr uint64_t kSignificandMask = 0x000FFFFFFFFFFFFF; + constexpr int kPhysicalSignificandSize = 52; // Excludes the hidden bit. + constexpr int kExponentBias = 0x3FF + kPhysicalSignificandSize; + constexpr int kDenormalExponent = 1 - kExponentBias; + constexpr int kMaxExponent = 0x7FF - kExponentBias; + + while (f > kHiddenBit + kSignificandMask) { + f >>= 1; + e++; + } + if (e >= kMaxExponent) { + return std::numeric_limits::infinity(); + } + if (e < kDenormalExponent) { + return 0.0; + } + while (e > kDenormalExponent && (f & kHiddenBit) == 0) { + f <<= 1; + e--; + } + + uint64_t biased_exponent; + if (e == kDenormalExponent && (f & kHiddenBit) == 0) + biased_exponent = 0; + else + biased_exponent = static_cast(e + kExponentBias); + + uint64_t bits = (f & kSignificandMask) | (biased_exponent << kPhysicalSignificandSize); + return reinterpret_bits(bits); +} + +TEST_CASE("digit gen") +{ + SECTION("single precision") + { + auto check_float = [](float number, const std::string& digits, int expected_exponent) + { + CAPTURE(number); + CAPTURE(digits); + CAPTURE(expected_exponent); + + char buf[32]; + int len = 0; + int exponent = 0; + nlohmann::detail::dtoa_impl::grisu2(buf, len, exponent, number); + + CHECK(digits == std::string(buf, buf + len)); + CHECK(expected_exponent == exponent); + }; + + check_float(make_float(0, 0, 0x00000001), "1", -45); // min denormal + check_float(make_float(0, 0, 0x007FFFFF), "11754942", -45); // max denormal + check_float(make_float(0, 1, 0x00000000), "11754944", -45); // min normal + check_float(make_float(0, 1, 0x00000001), "11754945", -45); + check_float(make_float(0, 1, 0x007FFFFF), "23509886", -45); + check_float(make_float(0, 2, 0x00000000), "23509887", -45); + check_float(make_float(0, 2, 0x00000001), "2350989", -44); + check_float(make_float(0, 24, 0x00000000), "98607613", -39); // fail if no special case in normalized boundaries + check_float(make_float(0, 30, 0x00000000), "63108872", -37); // fail if no special case in normalized boundaries + check_float(make_float(0, 31, 0x00000000), "12621775", -36); // fail if no special case in normalized boundaries + check_float(make_float(0, 57, 0x00000000), "84703295", -29); // fail if no special case in normalized boundaries + check_float(make_float(0, 254, 0x007FFFFE), "34028233", 31); + check_float(make_float(0, 254, 0x007FFFFF), "34028235", 31); // max normal + + // V. Paxson and W. Kahan, "A Program for Testing IEEE Binary-Decimal Conversion", manuscript, May 1991, + // ftp://ftp.ee.lbl.gov/testbase-report.ps.Z (report) + // ftp://ftp.ee.lbl.gov/testbase.tar.Z (program) + + // Table 16: Stress Inputs for Converting 24-bit Binary to Decimal, < 1/2 ULP + check_float(make_float(12676506, -102), "25", -25); + check_float(make_float(12676506, -103), "125", -26); + check_float(make_float(15445013, 86), "1195", 30); + check_float(make_float(13734123, -138), "39415", -39); + check_float(make_float(12428269, -130), "913085", -38); + check_float(make_float(15334037, -146), "1719005", -43); + check_float(make_float(11518287, -41), "52379105", -13); + check_float(make_float(12584953, -145), "2821644", -43); + check_float(make_float(15961084, -125), "37524328", -38); + check_float(make_float(14915817, -146), "16721209", -44); + check_float(make_float(10845484, -102), "21388946", -31); + check_float(make_float(16431059, -61), "7125836", -18); + + // Table 17: Stress Inputs for Converting 24-bit Binary to Decimal, > 1/2 ULP + check_float(make_float(16093626, 69), "95", 26); + check_float(make_float( 9983778, 25), "335", 12); + check_float(make_float(12745034, 104), "2585", 35); + check_float(make_float(12706553, 72), "60005", 24); + check_float(make_float(11005028, 45), "387205", 15); + check_float(make_float(15059547, 71), "3555835", 22); + check_float(make_float(16015691, -99), "25268305", -30); + check_float(make_float( 8667859, 56), "6245851", 17); + check_float(make_float(14855922, -82), "30721327", -25); + check_float(make_float(14855922, -83), "15360663", -25); + check_float(make_float(10144164, -110), "781478", -32); + check_float(make_float(13248074, 95), "52481028", 28); + } + + SECTION("double precision") + { + auto check_double = [](double number, const std::string& digits, int expected_exponent) + { + CAPTURE(number); + CAPTURE(digits); + CAPTURE(expected_exponent); + + char buf[32]; + int len = 0; + int exponent = 0; + nlohmann::detail::dtoa_impl::grisu2(buf, len, exponent, number); + + CHECK(digits == std::string(buf, buf + len)); + CHECK(expected_exponent == exponent); + }; + + check_double(make_double(0, 0, 0x0000000000000001), "5", -324); // min denormal + check_double(make_double(0, 0, 0x000FFFFFFFFFFFFF), "2225073858507201", -323); // max denormal + check_double(make_double(0, 1, 0x0000000000000000), "22250738585072014", -324); // min normal + check_double(make_double(0, 1, 0x0000000000000001), "2225073858507202", -323); + check_double(make_double(0, 1, 0x000FFFFFFFFFFFFF), "44501477170144023", -324); + check_double(make_double(0, 2, 0x0000000000000000), "4450147717014403", -323); + check_double(make_double(0, 2, 0x0000000000000001), "4450147717014404", -323); + check_double(make_double(0, 4, 0x0000000000000000), "17800590868057611", -323); // fail if no special case in normalized boundaries + check_double(make_double(0, 5, 0x0000000000000000), "35601181736115222", -323); // fail if no special case in normalized boundaries + check_double(make_double(0, 6, 0x0000000000000000), "7120236347223045", -322); // fail if no special case in normalized boundaries + check_double(make_double(0, 10, 0x0000000000000000), "11392378155556871", -321); // fail if no special case in normalized boundaries + check_double(make_double(0, 2046, 0x000FFFFFFFFFFFFE), "17976931348623155", 292); + check_double(make_double(0, 2046, 0x000FFFFFFFFFFFFF), "17976931348623157", 292); // max normal + + // Test different paths in DigitGen + check_double( 10000, "1", 4); + check_double( 1200000, "12", 5); + check_double(4.9406564584124654e-324, "5", -324); // exit integral loop + check_double(2.2250738585072009e-308, "2225073858507201", -323); // exit fractional loop + check_double( 1.82877982605164e-99, "182877982605164", -113); + check_double( 1.1505466208671903e-09, "11505466208671903", -25); + check_double( 5.5645893133766722e+20, "5564589313376672", 5); + check_double( 53.034830388866226, "53034830388866226", -15); + check_double( 0.0021066531670178605, "21066531670178605", -19); + + // V. Paxson and W. Kahan, "A Program for Testing IEEE Binary-Decimal Conversion", manuscript, May 1991, + // ftp://ftp.ee.lbl.gov/testbase-report.ps.Z (report) + // ftp://ftp.ee.lbl.gov/testbase.tar.Z (program) + + // Table 3: Stress Inputs for Converting 53-bit Binary to Decimal, < 1/2 ULP + check_double(make_double(8511030020275656, -342) /* 9.5e-088 */, "95", -89); + check_double(make_double(5201988407066741, -824) /* 4.65e-233 */, "465", -235); + check_double(make_double(6406892948269899, +237) /* 1.415e+087 */, "1415", 84); + check_double(make_double(8431154198732492, +72) /* 3.9815e+037 */, "39815", 33); + check_double(make_double(6475049196144587, +99) /* 4.10405e+045 */, "410405", 40); + check_double(make_double(8274307542972842, +726) /* 2.920845e+234 */, "2920845", 228); + check_double(make_double(5381065484265332, -456) /* 2.8919465e-122 */, "28919465", -129); + check_double(make_double(6761728585499734, -1057) /* 4.37877185e-303 */, "437877185", -311); + check_double(make_double(7976538478610756, +376) /* 1.227701635e+129 */, "1227701635", 120); + check_double(make_double(5982403858958067, +377) /* 1.8415524525e+129 */, "18415524525", 119); + check_double(make_double(5536995190630837, +93) /* 5.48357443505e+043 */, "548357443505", 32); + check_double(make_double(7225450889282194, +710) /* 3.891901811465e+229 */, "3891901811465", 217); + check_double(make_double(7225450889282194, +709) /* 1.9459509057325e+229 */, "19459509057325", 216); + check_double(make_double(8703372741147379, +117) /* 1.44609583816055e+051 */, "144609583816055", 37); + check_double(make_double(8944262675275217, -1001) /* 4.173677474585315e-286 */, "4173677474585315", -301); + check_double(make_double(7459803696087692, -707) /* 1.1079507728788885e-197 */, "11079507728788885", -213); + check_double(make_double(6080469016670379, -381) /* 1.234550136632744e-099 */, "1234550136632744", -114); + check_double(make_double(8385515147034757, +721) /* 9.2503171196036502e+232 */, "925031711960365", 218); + check_double(make_double(7514216811389786, -828) /* 4.1980471502848898e-234 */, "419804715028489", -248); + check_double(make_double(8397297803260511, -345) /* 1.1716315319786511e-088 */, "11716315319786511", -104); + check_double(make_double(6733459239310543, +202) /* 4.3281007284461249e+076 */, "4328100728446125", 61); + check_double(make_double(8091450587292794, -473) /* 3.3177101181600311e-127 */, "3317710118160031", -142); + + // Table 4: Stress Inputs for Converting 53-bit Binary to Decimal, > 1/2 ULP + check_double(make_double(6567258882077402, +952) /* 2.5e+302 */, "25", 301); + check_double(make_double(6712731423444934, +535) /* 7.55e+176 */, "755", 174); + check_double(make_double(6712731423444934, +534) /* 3.775e+176 */, "3775", 173); + check_double(make_double(5298405411573037, -957) /* 4.3495e-273 */, "43495", -277); + check_double(make_double(5137311167659507, -144) /* 2.30365e-028 */, "230365", -33); + check_double(make_double(6722280709661868, +363) /* 1.263005e+125 */, "1263005", 119); + check_double(make_double(5344436398034927, -169) /* 7.1422105e-036 */, "71422105", -43); + check_double(make_double(8369123604277281, -853) /* 1.39345735e-241 */, "139345735", -249); + check_double(make_double(8995822108487663, -780) /* 1.414634485e-219 */, "1414634485", -228); + check_double(make_double(8942832835564782, -383) /* 4.5392779195e-100 */, "45392779195", -110); + check_double(make_double(8942832835564782, -384) /* 2.26963895975e-100 */, "226963895975", -111); + check_double(make_double(8942832835564782, -385) /* 1.134819479875e-100 */, "1134819479875", -112); + check_double(make_double(6965949469487146, -249) /* 7.7003665618895e-060 */, "77003665618895", -73); + check_double(make_double(6965949469487146, -250) /* 3.85018328094475e-060 */, "385018328094475", -74); + check_double(make_double(6965949469487146, -251) /* 1.925091640472375e-060 */, "1925091640472375", -75); + check_double(make_double(7487252720986826, +548) /* 6.8985865317742005e+180 */, "68985865317742005", 164); + check_double(make_double(5592117679628511, +164) /* 1.3076622631878654e+065 */, "13076622631878654", 49); + check_double(make_double(8887055249355788, +665) /* 1.3605202075612124e+216 */, "13605202075612124", 200); + check_double(make_double(6994187472632449, +690) /* 3.5928102174759597e+223 */, "35928102174759597", 207); + check_double(make_double(8797576579012143, +588) /* 8.9125197712484552e+192 */, "8912519771248455", 177); + check_double(make_double(7363326733505337, +272) /* 5.5876975736230114e+097 */, "55876975736230114", 81); + check_double(make_double(8549497411294502, -448) /* 1.1762578307285404e-119 */, "11762578307285404", -135); + + // Table 20: Stress Inputs for Converting 56-bit Binary to Decimal, < 1/2 ULP + check_double(make_double(50883641005312716, -172) /* 8.4999999999999993e-036 */, "8499999999999999", -51); + check_double(make_double(38162730753984537, -170) /* 2.5499999999999999e-035 */, "255", -37); + check_double(make_double(50832789069151999, -101) /* 2.0049999999999997e-014 */, "20049999999999997", -30); + check_double(make_double(51822367833714164, -109) /* 7.9844999999999994e-017 */, "7984499999999999", -32); + check_double(make_double(66840152193508133, -172) /* 1.1165499999999999e-035 */, "11165499999999999", -51); + check_double(make_double(55111239245584393, -138) /* 1.581615e-025 */, "1581615", -31); + check_double(make_double(71704866733321482, -112) /* 1.3809855e-017 */, "13809855", -24); + check_double(make_double(67160949328233173, -142) /* 1.2046404499999999e-026 */, "12046404499999999", -42); + check_double(make_double(53237141308040189, -152) /* 9.3251405449999991e-030 */, "9325140544999999", -45); + check_double(make_double(62785329394975786, -112) /* 1.2092014595e-017 */, "12092014595", -27); + check_double(make_double(48367680154689523, -77) /* 3.2007045838499998e-007 */, "320070458385", -18); + check_double(make_double(42552223180606797, -102) /* 8.391946324354999e-015 */, "8391946324354999", -30); + check_double(make_double(63626356173011241, -112) /* 1.2253990460585e-017 */, "12253990460585", -30); + check_double(make_double(43566388595783643, -99) /* 6.8735641489760495e-014 */, "687356414897605", -28); + check_double(make_double(54512669636675272, -159) /* 7.459816430480385e-032 */, "7459816430480385", -47); + check_double(make_double(52306490527514614, -167) /* 2.7960588398142552e-034 */, "2796058839814255", -49); + check_double(make_double(52306490527514614, -168) /* 1.3980294199071276e-034 */, "13980294199071276", -50); + check_double(make_double(41024721590449423, -89) /* 6.6279012373057359e-011 */, "6627901237305736", -26); + check_double(make_double(37664020415894738, -132) /* 6.9177880043968072e-024 */, "6917788004396807", -39); + check_double(make_double(37549883692866294, -93) /* 3.7915693108349708e-012 */, "3791569310834971", -27); + check_double(make_double(69124110374399839, -104) /* 3.4080817676591365e-015 */, "34080817676591365", -31); + check_double(make_double(69124110374399839, -105) /* 1.7040408838295683e-015 */, "17040408838295683", -31); + + // Table 21: Stress Inputs for Converting 56-bit Binary to Decimal, > 1/2 ULP + check_double(make_double(49517601571415211, -94) /* 2.4999999999999998e-012 */, "25", -13); + check_double(make_double(49517601571415211, -95) /* 1.2499999999999999e-012 */, "125", -14); + check_double(make_double(54390733528642804, -133) /* 4.9949999999999996e-024 */, "49949999999999996", -40); // shortest: 4995e-27 + check_double(make_double(71805402319113924, -157) /* 3.9304999999999998e-031 */, "39304999999999998", -47); // shortest: 39305e-35 + check_double(make_double(40435277969631694, -179) /* 5.2770499999999992e-038 */, "5277049999999999", -53); + check_double(make_double(57241991568619049, -165) /* 1.223955e-033 */, "1223955", -39); + check_double(make_double(65224162876242886, +58) /* 1.8799584999999998e+034 */, "18799584999999998", 18); + check_double(make_double(70173376848895368, -138) /* 2.01387715e-025 */, "201387715", -33); + check_double(make_double(37072848117383207, -99) /* 5.8490641049999989e-014 */, "5849064104999999", -29); + check_double(make_double(56845051585389697, -176) /* 5.9349003054999999e-037 */, "59349003055", -47); + check_double(make_double(54791673366936431, -145) /* 1.2284718039499998e-027 */, "12284718039499998", -43); + check_double(make_double(66800318669106231, -169) /* 8.9270767180849991e-035 */, "8927076718084999", -50); + check_double(make_double(66800318669106231, -170) /* 4.4635383590424995e-035 */, "44635383590424995", -51); + check_double(make_double(66574323440112438, -119) /* 1.0016990862549499e-019 */, "10016990862549499", -35); + check_double(make_double(65645179969330963, -173) /* 5.4829412628024647e-036 */, "5482941262802465", -51); + check_double(make_double(61847254334681076, -109) /* 9.5290783281036439e-017 */, "9529078328103644", -32); + check_double(make_double(39990712921393606, -145) /* 8.9662279366405553e-028 */, "8966227936640555", -43); + check_double(make_double(59292318184400283, -149) /* 8.3086234418058538e-029 */, "8308623441805854", -44); + check_double(make_double(69116558615326153, -143) /* 6.1985873566126555e-027 */, "61985873566126555", -43); + check_double(make_double(69116558615326153, -144) /* 3.0992936783063277e-027 */, "30992936783063277", -43); + check_double(make_double(39462549494468513, -152) /* 6.9123512506176015e-030 */, "6912351250617602", -45); + check_double(make_double(39462549494468513, -153) /* 3.4561756253088008e-030 */, "3456175625308801", -45); + } +} + +TEST_CASE("formatting") +{ + SECTION("single precision") + { + auto check_float = [](float number, const std::string& expected) + { + char buf[32]; + char* end = nlohmann::detail::to_chars(buf, buf + 32, number); + std::string actual(buf, end); + + CHECK(actual == expected); + }; + // %.9g + check_float( -1.2345e-22f, "-1.2345e-22" ); // -1.23450004e-22 + check_float( -1.2345e-21f, "-1.2345e-21" ); // -1.23450002e-21 + check_float( -1.2345e-20f, "-1.2345e-20" ); // -1.23450002e-20 + check_float( -1.2345e-19f, "-1.2345e-19" ); // -1.23449999e-19 + check_float( -1.2345e-18f, "-1.2345e-18" ); // -1.23449996e-18 + check_float( -1.2345e-17f, "-1.2345e-17" ); // -1.23449998e-17 + check_float( -1.2345e-16f, "-1.2345e-16" ); // -1.23449996e-16 + check_float( -1.2345e-15f, "-1.2345e-15" ); // -1.23450002e-15 + check_float( -1.2345e-14f, "-1.2345e-14" ); // -1.23450004e-14 + check_float( -1.2345e-13f, "-1.2345e-13" ); // -1.23449997e-13 + check_float( -1.2345e-12f, "-1.2345e-12" ); // -1.23450002e-12 + check_float( -1.2345e-11f, "-1.2345e-11" ); // -1.2345e-11 + check_float( -1.2345e-10f, "-1.2345e-10" ); // -1.2345e-10 + check_float( -1.2345e-9f, "-1.2345e-09" ); // -1.23449995e-09 + check_float( -1.2345e-8f, "-1.2345e-08" ); // -1.23449997e-08 + check_float( -1.2345e-7f, "-1.2345e-07" ); // -1.23449993e-07 + check_float( -1.2345e-6f, "-1.2345e-06" ); // -1.23450002e-06 + check_float( -1.2345e-5f, "-1.2345e-05" ); // -1.2345e-05 + check_float( -1.2345e-4f, "-0.00012345" ); // -0.000123449994 + check_float( -1.2345e-3f, "-0.0012345" ); // -0.00123449997 + check_float( -1.2345e-2f, "-0.012345" ); // -0.0123450002 + check_float( -1.2345e-1f, "-0.12345" ); // -0.123450004 + check_float( -0.0f, "-0.0" ); // -0 + check_float( 0.0f, "0.0" ); // 0 + check_float( 1.2345e+0f, "1.2345" ); // 1.23450005 + check_float( 1.2345e+1f, "12.345" ); // 12.3450003 + check_float( 1.2345e+2f, "123.45" ); // 123.449997 + check_float( 1.2345e+3f, "1234.5" ); // 1234.5 + check_float( 1.2345e+4f, "12345.0" ); // 12345 + check_float( 1.2345e+5f, "123450.0" ); // 123450 + check_float( 1.2345e+6f, "1.2345e+06" ); // 1234500 + check_float( 1.2345e+7f, "1.2345e+07" ); // 12345000 + check_float( 1.2345e+8f, "1.2345e+08" ); // 123450000 + check_float( 1.2345e+9f, "1.2345e+09" ); // 1.23449997e+09 + check_float( 1.2345e+10f, "1.2345e+10" ); // 1.23449999e+10 + check_float( 1.2345e+11f, "1.2345e+11" ); // 1.23449999e+11 + check_float( 1.2345e+12f, "1.2345e+12" ); // 1.23450006e+12 + check_float( 1.2345e+13f, "1.2345e+13" ); // 1.23449995e+13 + check_float( 1.2345e+14f, "1.2345e+14" ); // 1.23450002e+14 + check_float( 1.2345e+15f, "1.2345e+15" ); // 1.23450003e+15 + check_float( 1.2345e+16f, "1.2345e+16" ); // 1.23449998e+16 + check_float( 1.2345e+17f, "1.2345e+17" ); // 1.23449996e+17 + check_float( 1.2345e+18f, "1.2345e+18" ); // 1.23450004e+18 + check_float( 1.2345e+19f, "1.2345e+19" ); // 1.23449999e+19 + check_float( 1.2345e+20f, "1.2345e+20" ); // 1.23449999e+20 + check_float( 1.2345e+21f, "1.2345e+21" ); // 1.23449999e+21 + check_float( 1.2345e+22f, "1.2345e+22" ); // 1.23450005e+22 + } + + SECTION("double precision") + { + auto check_double = [](double number, const std::string& expected) + { + char buf[32]; + char* end = nlohmann::detail::to_chars(buf, buf + 32, number); + std::string actual(buf, end); + + CHECK(actual == expected); + }; + // dtoa %.15g %.17g shortest + check_double( -1.2345e-22, "-1.2345e-22" ); // -1.2345e-22 -1.2345000000000001e-22 -1.2345e-22 + check_double( -1.2345e-21, "-1.2345e-21" ); // -1.2345e-21 -1.2345000000000001e-21 -1.2345e-21 + check_double( -1.2345e-20, "-1.2345e-20" ); // -1.2345e-20 -1.2345e-20 -1.2345e-20 + check_double( -1.2345e-19, "-1.2345e-19" ); // -1.2345e-19 -1.2345000000000001e-19 -1.2345e-19 + check_double( -1.2345e-18, "-1.2345e-18" ); // -1.2345e-18 -1.2345000000000001e-18 -1.2345e-18 + check_double( -1.2345e-17, "-1.2345e-17" ); // -1.2345e-17 -1.2345e-17 -1.2345e-17 + check_double( -1.2345e-16, "-1.2345e-16" ); // -1.2345e-16 -1.2344999999999999e-16 -1.2345e-16 + check_double( -1.2345e-15, "-1.2345e-15" ); // -1.2345e-15 -1.2345e-15 -1.2345e-15 + check_double( -1.2345e-14, "-1.2345e-14" ); // -1.2345e-14 -1.2345e-14 -1.2345e-14 + check_double( -1.2345e-13, "-1.2345e-13" ); // -1.2345e-13 -1.2344999999999999e-13 -1.2345e-13 + check_double( -1.2345e-12, "-1.2345e-12" ); // -1.2345e-12 -1.2345e-12 -1.2345e-12 + check_double( -1.2345e-11, "-1.2345e-11" ); // -1.2345e-11 -1.2345e-11 -1.2345e-11 + check_double( -1.2345e-10, "-1.2345e-10" ); // -1.2345e-10 -1.2345e-10 -1.2345e-10 + check_double( -1.2345e-9, "-1.2345e-09" ); // -1.2345e-09 -1.2345e-09 -1.2345e-9 + check_double( -1.2345e-8, "-1.2345e-08" ); // -1.2345e-08 -1.2345000000000001e-08 -1.2345e-8 + check_double( -1.2345e-7, "-1.2345e-07" ); // -1.2345e-07 -1.2345000000000001e-07 -1.2345e-7 + check_double( -1.2345e-6, "-1.2345e-06" ); // -1.2345e-06 -1.2345e-06 -1.2345e-6 + check_double( -1.2345e-5, "-1.2345e-05" ); // -1.2345e-05 -1.2345e-05 -1.2345e-5 + check_double( -1.2345e-4, "-0.00012345" ); // -0.00012345 -0.00012344999999999999 -0.00012345 + check_double( -1.2345e-3, "-0.0012345" ); // -0.0012345 -0.0012344999999999999 -0.0012345 + check_double( -1.2345e-2, "-0.012345" ); // -0.012345 -0.012345 -0.012345 + check_double( -1.2345e-1, "-0.12345" ); // -0.12345 -0.12345 -0.12345 + check_double( -0.0, "-0.0" ); // -0 -0 -0 + check_double( 0.0, "0.0" ); // 0 0 0 + check_double( 1.2345e+0, "1.2345" ); // 1.2345 1.2344999999999999 1.2345 + check_double( 1.2345e+1, "12.345" ); // 12.345 12.345000000000001 12.345 + check_double( 1.2345e+2, "123.45" ); // 123.45 123.45 123.45 + check_double( 1.2345e+3, "1234.5" ); // 1234.5 1234.5 1234.5 + check_double( 1.2345e+4, "12345.0" ); // 12345 12345 12345 + check_double( 1.2345e+5, "123450.0" ); // 123450 123450 123450 + check_double( 1.2345e+6, "1234500.0" ); // 1234500 1234500 1234500 + check_double( 1.2345e+7, "12345000.0" ); // 12345000 12345000 12345000 + check_double( 1.2345e+8, "123450000.0" ); // 123450000 123450000 123450000 + check_double( 1.2345e+9, "1234500000.0" ); // 1234500000 1234500000 1234500000 + check_double( 1.2345e+10, "12345000000.0" ); // 12345000000 12345000000 12345000000 + check_double( 1.2345e+11, "123450000000.0" ); // 123450000000 123450000000 123450000000 + check_double( 1.2345e+12, "1234500000000.0" ); // 1234500000000 1234500000000 1234500000000 + check_double( 1.2345e+13, "12345000000000.0" ); // 12345000000000 12345000000000 12345000000000 + check_double( 1.2345e+14, "123450000000000.0" ); // 123450000000000 123450000000000 123450000000000 + check_double( 1.2345e+15, "1.2345e+15" ); // 1.2345e+15 1234500000000000 1.2345e15 + check_double( 1.2345e+16, "1.2345e+16" ); // 1.2345e+16 12345000000000000 1.2345e16 + check_double( 1.2345e+17, "1.2345e+17" ); // 1.2345e+17 1.2345e+17 1.2345e17 + check_double( 1.2345e+18, "1.2345e+18" ); // 1.2345e+18 1.2345e+18 1.2345e18 + check_double( 1.2345e+19, "1.2345e+19" ); // 1.2345e+19 1.2345e+19 1.2345e19 + check_double( 1.2345e+20, "1.2345e+20" ); // 1.2345e+20 1.2345e+20 1.2345e20 + check_double( 1.2345e+21, "1.2344999999999999e+21" ); // 1.2345e+21 1.2344999999999999e+21 1.2345e21 + check_double( 1.2345e+22, "1.2345e+22" ); // 1.2345e+22 1.2345e+22 1.2345e22 + } +}