class Solution {
public:
    int strToInt(string str) {
        int k = 0; 
        //去空格
        while(k < str.size() && str[k] == ' ') k++;
        bool is_minus = false;
        long long num = 0;
        //判正负
        if(str[k] == '+') k++;
        else if(str[k] == '-') k++, is_minus = true;
        //字符变数字
        while(k < str.size() && str[k] >= '0' && str[k] <= '9') {
            num = num * 10 + str[k] - '0';
            k++;
        }
        //处理特例
        if(is_minus) num *= -1;
        if(num > INT_MAX) num = INT_MAX;
        if(num < INT_MIN) num = INT_MIN;
        return (int) num;
    }
};