atou: chars to unsigned

Functions
template<class T >
bool	c4::atou (csubstr str, T *v) noexcept
	Convert a trimmed string to an unsigned integral value. More...
template<class T >
size_t	c4::atou_first (csubstr str, T *v)
	Select the next range of characters in the string that can be parsed as an unsigned integral value, and convert it using atou(). More...

Detailed Description

Function Documentation

template<class T >

bool c4::atou ( csubstr  str, T *  v  )

noexcept

Convert a trimmed string to an unsigned integral value.

The string can be formatted as decimal, binary (prefix 0b or 0B), octal (prefix 0o or 0O) or hexadecimal (prefix 0x or 0X). Every character in the input string is read for the conversion; it must not contain any leading or trailing whitespace.

Returns

true if the conversion was successful.

Note

overflow is not detected: the return status is true even if the conversion would return a value outside of the type's range, in which case the result will wrap around the type's range. See overflows: does a number string overflow a type and Check read for overflow for overflow checking utilities.

If the string has a minus character, the return status will be false.

See also

atou_first() if the string is not trimmed to the value to read.

Definition at line 1558 of file charconv.hpp.

Referenced by c4::atou_first(), c4::atox(), and c4::from_chars().

{
    C4_STATIC_ASSERT(std::is_integral<T>::value);

    if C4_UNLIKELY(str.len == 0 || str.front() == '-')
        return false;

    bool parsed_ok = true;
    if(str.str[0] != '0')
    {
        parsed_ok = read_dec(str, v);
    }
    else
    {
        if(str.len > 1)
        {
            const char pfx = str.str[1];
            if(pfx == 'x' || pfx == 'X')
                parsed_ok = str.len > 2 && read_hex(str.sub(2), v);
            else if(pfx == 'b' || pfx == 'B')
                parsed_ok = str.len > 2 && read_bin(str.sub(2), v);
            else if(pfx == 'o' || pfx == 'O')
                parsed_ok = str.len > 2 && read_oct(str.sub(2), v);
            else
                parsed_ok = read_dec(str, v);
        }
        else
        {
            *v = 0; // we know the first character is 0
        }
    }
    return parsed_ok;
}

template<class T >

size_t c4::atou_first ( csubstr  str, T *  v  )

inline

Select the next range of characters in the string that can be parsed as an unsigned integral value, and convert it using atou().

Leading whitespace (space, newline, tabs) is skipped.

Returns

the number of characters read for conversion, or csubstr::npos if the conversion faileds

See also

atou() if the string is already trimmed to the value to read.

csubstr::first_uint_span()

Definition at line 1600 of file charconv.hpp.

Referenced by c4::from_chars_first().

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