public int myAtoi(String str) {
        if (str == null || str.length() == 0)
            return 0;
        str = str.trim();
        
        char flag = ‘+‘;
        int i = 0;
        if (str.charAt(0) == ‘-‘) {
            flag = ‘-‘;
            i++;
        } else if (str.charAt(0) == ‘+‘) {
            i++;
        }
            
        int result = 0;
        
        while (str.length() > i && str.charAt(i) >= ‘0‘ && str.charAt(i) <= ‘9‘) {
            result = result * 10 + (str.charAt(i) - ‘0‘);
            i++;
        }
        
        if (flag == ‘-‘)
        result = 0-result;
 
        // handle max and min
        if (result > Integer.MAX_VALUE)
            return Integer.MAX_VALUE;
     
        if (result < Integer.MIN_VALUE)
            return Integer.MIN_VALUE;
     
        return (int) result;
    }