在进行字符转换数字的时候为什么得到的结果不是预期的呢

Question

#include <iostream>
using namespace std;
class Solution {
public:
   static long long myAtoi(string s) {
        auto it = s.begin();
        while ((*it == ' ') || (*it == '0'))
        {
            s.erase(it);
        }
        long long sum = 0;
        int flag = 1;
        auto cur = 0;
        while ((cur = s.find('-'))!=-1)
        {
      
            s.erase(cur,1);
                flag = -flag;

              
 
        }
        while ((cur = s.find( '+'))!=-1)
        {
            
               s.erase(cur,1);
        }
        for (auto it = s.begin();it!=s.end()-1; it++)
        {
      
            sum += sum * 10 + (*it- '0');
        }
        if (flag == -1)
            sum = -sum;
        return sum;
    }
};
void test()
{
    cout << Solution::myAtoi("426") << endl;

}
int main()
{
    test();
    return 0;
}

主函数中测试的输入的是42
但是输出的话就是46

xdm解答一下

Answer 1

 for (auto it = s.begin();it!=s.end(); it++)
        {
            sum = sum * 10 + (*it- '0');
        }

s.end()不能减去1，sum = ，不是sum +=