Loop help

[sgill1998]

So I need my main to loop back to asking for input after it provides an answer. I forgot to do this before creating my main. SOS need help putting my already built main in a loop that will continue after the answer is output.

#include <stack>
#include <iostream>
#include "calc_useful.h"
using namespace std;


int main()
{
// declare your stack here
  stack<int> stk;
  char c;
  int onenum, twonum;
  cout<<"Please enter your expression:\n";

  c = cin.get();// priming read for the sentinel loop.
    while(c != '\n')
    {
      if(isdigit(c)){
        cin.putback(c);
        cin>>onenum;
        stk.push(onenum);
        // stack operation here.
      }
      else if(isop(c))
      {
        // if the stack is empty here you have an error.
      if(stk.empty())
      {
        cout<<"Wrong Expression!"<<endl;
        return 0;
      }
      onenum = stk.top();
      stk.pop();
      if(stk.empty())
      {
        cout<<"Wrong Expression!"<<endl;
        return 0;
      }
      twonum = stk.top();
      stk.pop();
      onenum = evaluate(onenum,twonum,c);
      stk.push(onenum);
      // here is where you have to pop a couple of numbers,
      // apply the operator to the numbers
      // and then push the result back into the stack            
      }
        c = cin.get(); // reading at the bottom of the sentinel loop
    }
        // this is where you get your final answer off the stack
        // it should be the only number left on the stack at this point
    if(stk.empty())
    {
      cout<<"Wrong Expression!"<<endl;
      return 0;
    }
    onenum = stk.top();
    stk.pop();
    if(!stk.empty())
    {
      cout<<"Error. Insufficient operators for operands.\n";
      return -1;
    }
    cout<<"The answer is: "<< onenum<<endl; return 0;
}

[Repeater]

#include <stack>
#include <iostream>
#include "calc_useful.h"
using namespace std;


int main()
{
  while (true)
  {

      // all your code here

   }
}