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.

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.

Update (2015-02-10):
The signature of the C++ function had been updated. If >you still see your function signature accepts a const char * >argument, please click the reload button to reset your >code definition.

思路：atoi实现，特别注意各种特殊情况

class Solution {public:    int myAtoi(string str) {        if(str.size() == 0)        {            return 0;        }        int sum = 0;        int i = 0;        //去除首部的空格        while(str[i] == ' ')        {            i++;        }        //首字母为符号位        bool sign = true;        if(str[i] == '+')        {            i++;        }        else if(str[i] == '-')        {            sign = false;            i++;        }        for(;i<str.size();i++)        {            //字符非法            if(str[i] < '0' || str[i] > '9')            {                if(!sign)                {                    sum = -sum;                }                return sum;            }            //溢出            if((sum > INT_MAX/10) || (sum == INT_MAX/10 && (str[i]-'0') > INT_MAX%10))            {                if(sign)                {                    return INT_MAX;                }                return INT_MIN;            }            sum = sum*10 + (str[i]-'0');        }        if(!sign)        {            sum = -sum;        }        return sum;    }};