c++中的string相连问题！

我们定义string A，进行g++编译得：输出为空！很奇怪

#include<iostream>

#include<string>

using namespace std;

int main()

{     

string A="";      

      string str="1234";

      int i,j,n=2;

            for(i=0;i<n;i++)

                  {A[i]=str[i];}

                  A[i]='\0';

          cout<<A<<endl;

}

转载于:https://www.cnblogs.com/cxy931980808/p/6649085.html