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GH-49003: [C++] Don't consider out_of_range an error in float parsing #49095

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Merged
pitrou merged 1 commit into from
Feb 3, 2026
Merged

GH-49003: [C++] Don't consider out_of_range an error in float parsing #49095

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15 changes: 12 additions & 3 deletions cpp/src/arrow/util/value_parsing.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -35,15 +35,21 @@ bool StringToFloat(const char* s, size_t length, char decimal_point, float* out)
::arrow_vendored::fast_float::chars_format::general, decimal_point};
const auto res =
::arrow_vendored::fast_float::from_chars_advanced(s, s + length, *out, options);
return res.ec == std::errc() && res.ptr == s + length;
const bool is_valid_number =
res.ec == std::errc() || res.ec == std::errc::result_out_of_range;
const bool consumed_entire_string = res.ptr == s + length;
return is_valid_number && consumed_entire_string;
}

bool StringToFloat(const char* s, size_t length, char decimal_point, double* out) {
::arrow_vendored::fast_float::parse_options options{
::arrow_vendored::fast_float::chars_format::general, decimal_point};
const auto res =
::arrow_vendored::fast_float::from_chars_advanced(s, s + length, *out, options);
return res.ec == std::errc() && res.ptr == s + length;
const bool is_valid_number =
res.ec == std::errc() || res.ec == std::errc::result_out_of_range;
const bool consumed_entire_string = res.ptr == s + length;
return is_valid_number && consumed_entire_string;
}

// Half float
Expand All @@ -53,7 +59,10 @@ bool StringToFloat(const char* s, size_t length, char decimal_point, Float16* ou
float temp_out;
const auto res =
::arrow_vendored::fast_float::from_chars_advanced(s, s + length, temp_out, options);
const bool ok = res.ec == std::errc() && res.ptr == s + length;
const bool is_valid_number =
res.ec == std::errc() || res.ec == std::errc::result_out_of_range;
const bool consumed_entire_string = res.ptr == s + length;
const bool ok = is_valid_number && consumed_entire_string;
if (ok) {
*out = Float16::FromFloat(temp_out);
}
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12 changes: 12 additions & 0 deletions cpp/src/arrow/util/value_parsing_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -141,6 +141,10 @@ TEST(StringConversion, ToFloat) {
AssertConversion<FloatType>("0", 0.0f);
AssertConversion<FloatType>("-0.0", -0.0f);
AssertConversion<FloatType>("-1e20", -1e20f);
AssertConversion<FloatType>("4e38", std::numeric_limits<float>::infinity());
AssertConversion<FloatType>("-4e38", -std::numeric_limits<float>::infinity());
AssertConversion<FloatType>("1e-46", 0.0f);
AssertConversion<FloatType>("-1e-46", -0.0f);
AssertConversion<FloatType>("+Infinity", std::numeric_limits<float>::infinity());
AssertConversion<FloatType>("-Infinity", -std::numeric_limits<float>::infinity());
AssertConversion<FloatType>("Infinity", std::numeric_limits<float>::infinity());
Expand All @@ -166,6 +170,10 @@ TEST(StringConversion, ToDouble) {
AssertConversion<DoubleType>("0", 0);
AssertConversion<DoubleType>("-0.0", -0.0);
AssertConversion<DoubleType>("-1e100", -1e100);
AssertConversion<DoubleType>("2e308", std::numeric_limits<double>::infinity());
AssertConversion<DoubleType>("-2e308", -std::numeric_limits<double>::infinity());
AssertConversion<DoubleType>("1e-325", 0.0);
AssertConversion<DoubleType>("-1e-325", -0.0);
AssertConversion<DoubleType>("+Infinity", std::numeric_limits<double>::infinity());
AssertConversion<DoubleType>("-Infinity", -std::numeric_limits<double>::infinity());
AssertConversion<DoubleType>("Infinity", std::numeric_limits<double>::infinity());
Expand All @@ -185,6 +193,10 @@ TEST(StringConversion, ToHalfFloat) {
AssertConversion<HalfFloatType>("0", Float16(0.0f));
AssertConversion<HalfFloatType>("-0.0", Float16(-0.0f));
AssertConversion<HalfFloatType>("-1e15", Float16(-1e15));
AssertConversion<HalfFloatType>("7e4", Float16::FromBits(0x7c00));
AssertConversion<HalfFloatType>("-7e4", Float16::FromBits(0xfc00));
AssertConversion<HalfFloatType>("1e-9", Float16(0.0f));
AssertConversion<HalfFloatType>("-1e-9", Float16(-0.0f));
AssertConversion<HalfFloatType>("+Infinity", Float16::FromBits(0x7c00));
AssertConversion<HalfFloatType>("-Infinity", Float16::FromBits(0xfc00));
AssertConversion<HalfFloatType>("Infinity", Float16::FromBits(0x7c00));
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