8. String to Integer

Implement function atoi to convert a string to an integer.

If no valid conversion could be performed, a zero value is returned.

If the correct value is out of the range of representable values, INT_MAX(2147483647) or INT_MIN (-2147483648) is returned.

Example

"10" => 10
"-1" => -1
"123123123123123" => 2147483647
"1.0" => 1

public class Solution {
    public int myAtoi(String str) {
        if (str.isEmpty()) return 0;
        int sign = 1, base = 0, i = 0;
        while (i < str.length() && str.charAt(i) == ' ') {
            i++;
        }
        if (i == str.length()) return 0;
        if (str.charAt(i) == '-' || str.charAt(i) == '+') {
            sign = str.charAt(i) == '-' ? -1 : 1;
            i++;
        }
        while (i < str.length() && str.charAt(i) >= '0' && str.charAt(i) <= '9') {
            if (base > Integer.MAX_VALUE / 10 || (base == Integer.MAX_VALUE / 10 && str.charAt(i) - '0' > 7)) {
                return (sign == 1) ? Integer.MAX_VALUE : Integer.MIN_VALUE;
            }
            base = 10 * base + (str.charAt(i++) - '0');
        }
        return base * sign;

    }
}