这好像是阉割版分，以前做过一道各种字符都有,- -23这种类似的也需要考虑

class Solution {
public:
    int strToInt(string str) {
        int index = 0, len = str.length();
        double ans = 0;
        string buff = "";
        bool flag = false;
        while(index < len && str[index] == ' ') index++;

        if (str[index] == '-') {index++; flag = true;}
        else if (str[index] == '+') index++;
        if(str[index] >= '0' && str[index] <= '9') {
            while(str[index] >= '0' && str[index] <= '9') buff += str[index++];    
        }
        for (int i = 0; i < buff.length(); ++i) {
            ans += (buff[i] - '0') * pow(10, buff.length() - i - 1);
        }
        if (flag) ans *= -1;
        if (ans > INT_MAX) return INT_MAX;
        if (ans < INT_MIN) return INT_MIN;

        return (int)ans;
    }
};