Converting a string with a hexadecimal representation of a number to an actual numeric value

Question

I have a string like this:

\"00c4\"

And I need to convert it to the numeric value that would be expressed by the literal:

0         


        

Answer 1

int val_from_hex(char *hex_string) {
    char *c = hex_string;
    int val = 0;
    while(*c) {
        val <<= 4;
        if(*c >= '0' && *c <= '9')
            val += *c - '0';
        else if(*c >= 'a' && *c <= 'f')
            val += *c - 'a' + 10;
        c++;
    }
    return val;
}