Method myAtoi

src/main/java/com/thealgorithms/strings/MyAtoi.java:25–66

Converts the given string to a 32-bit signed integer. The conversion discards any leading whitespace characters until the first non-whitespace character is found. Then, it takes an optional initial plus or minus sign followed by as many numerical digits as possible and interprets them as a numerical

(String s)

     * @return the converted integer, or 0 if the string cannot be converted to a valid integer
     */
    public static int myAtoi(String s) {
        if (s == null || s.isEmpty()) {
            return 0;
        }

        s = s.trim();
        int length = s.length();
        if (length == 0) {
            return 0;
        }

        int index = 0;
        boolean negative = false;

        // Check for the sign
        if (s.charAt(index) == '-' || s.charAt(index) == '+') {
            negative = s.charAt(index) == '-';
            index++;
        }

        int number = 0;
        while (index < length) {
            char ch = s.charAt(index);

            // Accept only ASCII digits
            if (ch < '0' || ch > '9') {
                break;
            }

            int digit = ch - '0';

            // Check for overflow
            if (number > (Integer.MAX_VALUE - digit) / 10) {
                return negative ? Integer.MIN_VALUE : Integer.MAX_VALUE;
            }

            number = number * 10 + digit;
            index++;
        }

        return negative ? -number : number;
    }
}