Leetcode 8. 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.

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

思路：

1 如果出现字符 -> 则忽略

2 如果溢出overflow，返回最大值、最小值

3 符号位symbol

 public static int MyAtoi(string str)        {            if (str == null || str.Length == 0)                return 0;            bool isNeg = false;            str = str.Trim();            char[] charArray = str.ToCharArray();            int curIndex = 0;            //获取整数符号            if (charArray[0] == '+')            {                isNeg = false;                curIndex++;            }            else if (charArray[0] == '-')            {                isNeg = true;                curIndex++;            }            else                isNeg = false;            //把字符串转换为整数            Int64 num = 0, absnum = 0;            char c;            while (curIndex < str.Length)            {                c = charArray[curIndex];                if (!Char.IsDigit(c))                    break;                absnum = 10 * absnum + (c - '0');//c是字符串的asscii                if (isNeg)                    num = -absnum;                else                    num = absnum;                //判断是否溢出                if (num > Int32.MaxValue)                    return Int32.MaxValue;                if (num < Int32.MinValue)                    return Int32.MinValue;                curIndex++;            }            return (int)num;        }