leetcode-String to Integer (atoi)

class Solution {
public:
    int atoi(const char *str) 
    {
        bool negative = false;
        while(*str==' ')str++   ;
        if(*str=='-')
        {
            negative = true;
            str++;
        }
        else if(*str=='+')
            str++;
        long long  result = 0;
        while(*str!='')
        {
            if(*str>='0'&&*str<='9')
            {
                result = result * 10 + *str - '0';
                str++;
            }
            else
                break;
        }
    
            result =  negative?-result:result;
            if(result>INT_MAX)
                return INT_MAX;
            else if(result<INT_MIN)
                return INT_MIN;
            return result;
    }
};

考虑不周，错了好多次

1. +-2 --2 返回0

2. -  00023ea9返回 -23

3. 超过范围的