万能转换字符类型到int ，int到string，string到char or char *等等

std:: 可以不用写using namespace std;
std::cout 可以单独用

#include <iostream>     // std::cout, std::right, std::endl
#include <iomanip>   
#include<sstream>   // std::setw
using namespace std;

int main () {
  int val = 65; 
  
  string s1;
  stringstream ss;
  ss<<val;   //int ->string
  ss>>s1;
  s1+="123";
	cout<<s1;
	ss.clear();
	
	
	int a;
	ss<<s1;    //string->int 
	ss>>a;
	cout<<endl<<a+10000;
	
	ss.clear();
	char cc[10];
	ss<<s1;
	ss>>cc;   //string->char *
	cout<<cc<<endl;
 
	ss.clear();
	string s2;

	ss<<cc;
	ss>>s2;
		s2+="12sda2sd";
	cout<<s2<<endl; 
  return 0;
}