Read a value

Functions
template<class I>
bool	c4::read_dec (csubstr s, I *v) noexcept
	read a decimal integer from a string.
template<class I>
bool	c4::read_hex (csubstr s, I *v) noexcept
	read an hexadecimal integer from a string.
template<class I>
bool	c4::read_bin (csubstr s, I *v) noexcept
	read a binary integer from a string.
template<class I>
bool	c4::read_oct (csubstr s, I *v) noexcept
	read an octal integer from a string.

Detailed Description

Function Documentation

read_dec()

template<class I>

bool c4::read_dec ( csubstr s, I * v )

inlinenoexcept

read a decimal integer from a string.

This is the lowest level (and the fastest) function to do this task.

Note

does not accept negative numbers

The string must be trimmed. Whitespace is not accepted.

the string must not be empty

there is no check for overflow; the value wraps around in a way similar to the standard C/C++ overflow behavior. For example, read_dec<int8_t>("128", &val) returns true and val will be set to 0 because 127 is the max i8 value.

See also

overflows<T>() to find out if a number string overflows a type range

Returns

true if the conversion was successful (no overflow check)

Definition at line 874 of file charconv.hpp.

{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        if C4_UNLIKELY(c < '0' || c > '9')
            return false;
        *v = ((*v) * I(10)) + (I(c) - I('0'));
    }
    return true;
}

Referenced by atoi(), atou(), and read_dec().

read_hex()

template<class I>

bool c4::read_hex ( csubstr s, I * v )

inlinenoexcept

read an hexadecimal integer from a string.

This is the lowest level (and the fastest) function to do this task.

Note

does not accept negative numbers

does not accept leading 0x or 0X

the string must not be empty

the string must be trimmed. Whitespace is not accepted.

there is no check for overflow; the value wraps around in a way similar to the standard C/C++ overflow behavior. For example, read_hex<int8_t>("80", &val) returns true and val will be set to 0 because 7f is the max i8 value.

See also

overflows<T>() to find out if a number string overflows a type range

Returns

true if the conversion was successful (no overflow check)

Definition at line 902 of file charconv.hpp.

{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        I cv;
        if(c >= '0' && c <= '9')
            cv = I(c) - I('0');
        else if(c >= 'a' && c <= 'f')
            cv = I(10) + (I(c) - I('a'));
        else if(c >= 'A' && c <= 'F')
            cv = I(10) + (I(c) - I('A'));
        else
            return false;
        *v = ((*v) * I(16)) + cv;
    }
    return true;
}

Referenced by atoi(), atou(), and decode_code_point().

read_bin()

template<class I>

bool c4::read_bin ( csubstr s, I * v )

inlinenoexcept

read a binary integer from a string.

This is the lowest level (and the fastest) function to do this task.

Note

does not accept negative numbers

does not accept leading 0b or 0B

the string must not be empty

the string must be trimmed. Whitespace is not accepted.

there is no check for overflow; the value wraps around in a way similar to the standard C/C++ overflow behavior. For example, read_bin<int8_t>("10000000", &val) returns true and val will be set to 0 because 1111111 is the max i8 value.

See also

overflows<T>() to find out if a number string overflows a type range

Returns

true if the conversion was successful (no overflow check)

Definition at line 937 of file charconv.hpp.

{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        *v <<= 1;
        if(c == '1')
            *v |= 1;
        else if(c != '0')
            return false;
    }
    return true;
}

Referenced by atoi(), and atou().

read_oct()

template<class I>

bool c4::read_oct ( csubstr s, I * v )

inlinenoexcept

read an octal integer from a string.

This is the lowest level (and the fastest) function to do this task.

Note

does not accept negative numbers

does not accept leading 0o or 0O

the string must not be empty

the string must be trimmed. Whitespace is not accepted.

there is no check for overflow; the value wraps around in a way similar to the standard C/C++ overflow behavior. For example, read_oct<int8_t>("200", &val) returns true and val will be set to 0 because 177 is the max i8 value.

See also

overflows<T>() to find out if a number string overflows a type range

Returns

true if the conversion was successful (no overflow check)

Definition at line 967 of file charconv.hpp.

{
    C4_STATIC_ASSERT(std::is_integral<I>::value);
    C4_ASSERT(!s.empty());
    *v = 0;
    for(char c : s)
    {
        if C4_UNLIKELY(c < '0' || c > '7')
            return false;
        *v = ((*v) * I(8)) + (I(c) - I('0'));
    }
    return true;
}

Referenced by atoi(), and atou().