String to Integer

int strToInt( string str ){
    int i = 0, num = 0;
    bool isNeg = false;
    int len = str.Length();

    if( str[0] == '-' ){
        isNeg = true;
        i = 1;
    }

    while( i < len ){
        num *= 10;
        num += ( str[i++] - '0' );
    }

    if( isNeg )
        num *= -1;

    return num;
}