atoi from cplusplus

int atoi( char string[] )
{
    int sign     = 0, // whether the number is negative
        result   = 0, // result of conversion
        position = 0; // position in the string

    if ( string[0] == '-' ) // check for minus
    {
        position++; // skip this character when converting
        sign = 1;   // the number is negative
    }

    for ( ; string[position]; position++ ) // for each character in the ( \0 terminated ) string
    {
        result *= 10; // move the digits by one position
        result += string[position] - '0'; // get the number
    }

    if ( sign ) // if the number was negative
        result *= -1; //change the sign

    return result; // return the result
}