#include <sstream>
using namespace std;
int main()
{
stringstream string_to_int;
string s1="12345";
int n1;
string_to_int<<s1;
//也可以使用string_to_int.str(s1);
//或者 s1=string_to_int.str();
string_to_int>>n1;
cout<<"s1="<<s1<<endl;//s1=12345
cout<<"n1="<<n1<<endl;//n1=12345
}