LeetCode 8. string conversion integer (atoi) (String to Integer (atoi))

8. string conversion integer (atoi)
8. String to Integer (atoi)

Title Description

LeetCode

LeetCode 8. String to Integer (atoi) Medium

Java implementation

class Solution {
    public int myAtoi(String str) {
        if (str == null || str.trim().length() == 0) {
            return 0;
        }
        str = str.trim();
        char firstChar = str.charAt(0);
        int sign = 1, start = 0, len = str.length();
        long sum = 0;
        if (firstChar == '+') {
            sign = 1;
            start++;
        } else if (firstChar == '-') {
            sign = -1;
            start++;
        }
        for (int i = start; i < len; i++) {
            if (!Character.isDigit(str.charAt(i))) {
                return (int) sum * sign;
            }
            sum = sum * 10 + str.charAt(i) - '0';
            if (sign == 1 && sum > Integer.MAX_VALUE) {
                return Integer.MAX_VALUE;
            }
            if (sign == -1 && sign * sum < Integer.MIN_VALUE) {
                return Integer.MIN_VALUE;
            }
        }
        return (int) sum * sign;
    }
}

Similar topics

• 7. Reverse Reverse Integer Integer
• 65. Valid Number of significant figures

Reference material

• https://leetcode.com/problems/string-to-integer-atoi/
• https://leetcode-cn.com/problems/string-to-integer-atoi/