atof: chars to float32

Functions
bool	c4::atof (csubstr str, float *v) noexcept
	Convert a string to a single precision real number.
size_t	c4::atof_first (csubstr str, float *v) noexcept
	Convert a string to a single precision real number.

Detailed Description

Function Documentation

atof()

bool c4::atof ( csubstr str, float * v )

inlinenoexcept

Convert a string to a single precision real number.

The input string must be trimmed to the value, ie no leading or trailing whitespace can be present.

Returns

true iff the conversion succeeded

See also

atof_first() if the string is not trimmed

Definition at line 2120 of file charconv.hpp.

{
    C4_ASSERT(str.len > 0);
    C4_ASSERT(str.triml(" \r\t\n").len == str.len);
#if C4CORE_HAVE_FAST_FLOAT
    // fastfloat cannot parse hexadecimal floats
    bool isneg = (str.str[0] == '-');
    csubstr rem = str.sub(isneg || str.str[0] == '+');
    if(!(rem.len >= 2 && (rem.str[0] == '0' && (rem.str[1] == 'x' || rem.str[1] == 'X'))))
    {
        fast_float::from_chars_result result;
        result = fast_float::from_chars(str.str, str.str + str.len, *v);
        return result.ec == std::errc();
    }
    else if(detail::scan_rhex(rem.sub(2), v))
    {
        *v *= isneg ? -1.f : 1.f;
        return true;
    }
    return false;
#elif C4CORE_HAVE_STD_FROMCHARS
    std::from_chars_result result;
    result = std::from_chars(str.str, str.str + str.len, *v);
    return result.ec == std::errc();
#else
    csubstr rem = str.sub(str.str[0] == '-' || str.str[0] == '+');
    if(!(rem.len >= 2 && (rem.str[0] == '0' && (rem.str[1] == 'x' || rem.str[1] == 'X'))))
        return detail::scan_one(str, "f", v) != csubstr::npos;
    else
        return detail::scan_one(str, "a", v) != csubstr::npos;
#endif
}

atof_first()

size_t c4::atof_first ( csubstr str, float * v )

inlinenoexcept

Convert a string to a single precision real number.

Leading whitespace is skipped until valid characters are found.

Returns

the number of characters read from the string, or npos if conversion was not successful or if the string was empty

Definition at line 2158 of file charconv.hpp.

{
    csubstr trimmed = str.first_real_span();
    if(trimmed.len == 0)
        return csubstr::npos;
    if(atof(trimmed, v))
        return static_cast<size_t>(trimmed.end() - str.begin());
    return csubstr::npos;
}