string to integer (atoi)

Implement atoi to convert a string to an integer.

Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.

Notes: It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.

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Solution

public class  {
    public int myAtoi(String str) {
        int index = 0, total = 0, sign = 1;
        if(str.length() == 0) return 0;
        while(str.charAt(index) == ' ' && index < str.length()) 
            index++;
        
        if(str.charAt(index) == '+' || str.charAt(index) == '-') {
            sign = str.charAt(index)=='+'?1:-1;
            index++;
        }
        
        while(index < str.length()) {
            int digit = str.charAt(index) - '0';
            if(digit < 0 || digit > 9) break;
            if(total > Integer.MAX_VALUE/10 || (total == Integer.MAX_VALUE/10&& digit > Integer.MAX_VALUE%10)) {
                return sign==1?Integer.MAX_VALUE:Integer.MIN_VALUE;
            }
            total = total * 10 + digit;
            index++;
        }
        System.out.println(total);
        return total*sign;
    }
}

string to integer (atoi)

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