C++: Converting Hexadecimal to Decimal

Question

I\'m looking for a way to convert hex^{(hexadecimal)} to dec^(decimal) easily. I found an easy way to do this like :

Answer 1

This should work as well.

#include 
#include 

template
T Hex2Int(const char* const Hexstr, bool* Overflow)
{
    if (!Hexstr)
        return false;
    if (Overflow)
        *Overflow = false;

    auto between = [](char val, char c1, char c2) { return val >= c1 && val <= c2; };
    size_t len = strlen(Hexstr);
    T result = 0;

    for (size_t i = 0, offset = sizeof(T) << 3; i < len && (int)offset > 0; i++)
    {
        if (between(Hexstr[i], '0', '9'))
            result = result << 4 ^ Hexstr[i] - '0';
        else if (between(tolower(Hexstr[i]), 'a', 'f'))
            result = result << 4 ^ tolower(Hexstr[i]) - ('a' - 10); // Remove the decimal part;
        offset -= 4;
    }
    if (((len + ((len % 2) != 0)) << 2) > (sizeof(T) << 3) && Overflow)
        *Overflow = true;
    return result;
}

The 'Overflow' parameter is optional, so you can leave it NULL.

Example:

auto result = Hex2Int("C0ffee", NULL);
auto result2 = Hex2Int("DeadC0ffe", NULL);