While loop not going back into loop - loops

Question

I have been working on a project and I'm almost finish the last problem I have is creating a while loop that keeps asking the user if they want to convert an expression. So far it does it once then doesn't continue asking. I know this is a simple question and I think I have the logic down but for some reason it isn't working.
Here is my main:
int main(){
string answer=" ";
string expression;
while(answer!="no"){
cout<<"Would you like to do a conversion,type yes or no:";
getline(cin,answer);
cout<<" Enter a Post Fix expression:";
getline(cin,expression);
convert(expression);
}
return 0;
}
Though not really necessary for my question here is the code above my main in case it is useful:
/*
* PLEASE DO NOT PLACE A SPACE BEFORE YOU INPUT THE FIRST OPERAND
*
*
*/
#include "stack.h"
void convert(string expression){
stack k; //Stores raw input string
stack c; //stores input string without spaces
stack s;//stores the string values
string post =" ";
string rightop="";
string leftop="";
string op ="";
int countop=0;// counts the number of operators
int countoper=0;// counts the number of operands
for (int i =0; i<=expression.length()-1;i++){
k.push(expression[i]);
if(expression[i] == '*' ||
expression[i] == '+' ||
expression[i] == '-' ||
expression[i] == '/')
{
countop++;
}
}
c.push(expression[0]);
int count=expression.length()/2;
countoper=(count-countop)+1;
if (countop==countoper){ //tells when there are too many opertors and not enough operands
cout<<"too many operators and not enough operand"<<endl;
exit(1);
}
if(countop==countoper*2){ //tells when there are too many opertors and not enough operands
cout<<"too many operands and not enough operators"<<endl;
exit(1);
}
for(int i=1;i<=expression.length()/2;i++){
c.push(expression[2*i]);
}
for(int i=0; i<2;i++){
leftop=c.top();
c.pop();
rightop=c.top();
c.pop();
op=c.top();
c.pop();
post="(" + leftop + " " + op + " " + rightop + ")";
s.push(post);
if(count<6){
cout<<s.top()<<endl;
}
}
if (count>=6){
cout<<"(";
cout<<s.top();
cout<<c.top();
s.pop();
cout<<s.top();
cout<<")";
}
}

Answer 1

I tried this code, which I copied from yours, and it worked fine. Which made me arrive to the conclusion that I do not understand what the problem is or what you want.
#include <iostream>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int main(){
string answer=" ";
string expression;
while(answer!="no"){
cout<<"Would you like to do a conversion,type yes or no:";
getline(cin,answer);
cout<<" Enter a Post Fix expression:";
getline(cin,expression);
// do something
}
return 0;
}
What this is doing:
1) user answers "no" to first question, then user writes something on the second input. Exits program.
2) user answers something different from "no", then user writes something. Goes back to the first question.
What is the behaviour that you want? Explain better.

Answer 2

I also ran your code and the while loop worked for me.
Perhaps you can begin by commenting out your convert(expression); call and debugging from there!
#include <iostream>
using namespace std;
int main(){
string answer=" ";
string expression;
while(answer!="no"){
cout<<"Would you like to do a conversion,type yes or no:";
getline(cin,answer);
cout<<" Enter a Post Fix expression:";
getline(cin,expression);
/*convert(expression);*/
}
return 0;
}