Bug with integer parsing in MD_StringIsCStyleInt and MD_CStyleIntFromString

[EeroMutka]

Calling MD_StringIsCStyleInt(MD_S8Lit("0")) returns false and MD_CStyleIntFromString(MD_S8Lit("012345")) returns 5349.

Both functions handle radix parsing incorrectly. If the parser encounters a leading zero, but no "x" or "b", then you will get incorrect results.

Here are the functions after my fix:

MD_FUNCTION MD_b32
MD_StringIsCStyleInt(MD_String8 string)
{
    MD_u8 *ptr = string.str;
    MD_u8 *opl = string.str + string.size;
    
    // consume sign
    for (;ptr < opl && (*ptr == '+' || *ptr == '-'); ptr += 1);
    
    // radix from prefix
    MD_u32 radix = 10;
    if (ptr + 1 < opl && *ptr == '0')
    {
        MD_u8 c1 = ptr[1];
        if (c1 == 'x')
        {
            ptr += 2;
            radix = 0x10;
        }
        else if (c1 == 'b')
        {
            ptr += 2;
            radix = 2;
        }
    }
    
    // check integer "digits"
    MD_String8 digits_substr = MD_S8Range(ptr, opl);
    MD_b32 result = MD_StringIsU64(digits_substr, radix);
    
    return(result);
}

MD_FUNCTION MD_i64
MD_CStyleIntFromString(MD_String8 string)
{
    MD_u64 p = 0;
    
    // consume sign
    MD_i64 sign = +1;
    if (p < string.size)
    {
        MD_u8 c = string.str[p];
        if (c == '-')
        {
            sign = -1;
            p += 1;
        }
        else if (c == '+')
        {
            p += 1;
        }
    }
    
    // radix from prefix
    MD_u32 radix = 10;
    if (p + 1 < string.size && string.str[p] == '0')
    {
        MD_u8 c1 = string.str[p + 1];
        if (c1 == 'x')
        {
            p += 2;
            radix = 0x10;
        }
        else if (c1 == 'b')
        {
            p += 2;
            radix = 2;
        }
    }
    
    // consume integer "digits"
    MD_String8 digits_substr = MD_S8Skip(string, p);
    MD_u64 n = MD_U64FromString(digits_substr, radix);
    
    // combine result
    MD_i64 result = sign*n;
    return(result);
}