C++ code to add binary numbers using STL stack

Description:
Using STL ,the stack header file needs to be included to use this class. The class member functions that are provided are listed below.

• push, pushes an item onto the stack.
• pop, pops an item from the stack but does not give this item to the programmer to use.
• top, gives the programmer a reference to the top of stack item; no change is made to the stack.
• empty, the usual boolean function.
• size, reports the number of items on the stack.

Code:
#include<iostream.h>
#include<vector>
#include<stack>
using namespace std;
stack <int> read();
void display(stack<int> &s);
stack <int>add(stack<int> &s1,stack<int> &s2);
void main()
{
stack<int> s1,s2,s3;
int ch;
do
{
cout<<”\n1.Addition of two binary numbers\n2.Quit”;
cout<<”\nEnter your choice:”;
cin>>ch;
switch(ch)
{
case 1: s1=read();
s2=read();
s3=add(s1,s2);
display(s3);
break;
}
}while(ch!=2);
}
stack<int> read()
{
char a[40];
stack<int> s;
cout<<”\n Enter a binary number: “;
cin>>a;
for(int i=0;a[i]!=’\0′;i++)
{
if(a[i]==’1′)
s.push(1);
else
if(a[i]==’0′)
s.push(0);
}
return s;
}
stack<int> add(stack<int> &s1,stack<int> &s2)
{
stack<int> s;
int sum,carry=0,bit1,bit2;
while(!s1.empty() || !s2.empty())
{
bit1=bit2=0;
if(!s1.empty())
{
bit1=s1.top();
s1.pop();
}
if(!s2.empty())
{
bit2=s2.top();
s2.pop();
}
sum=(bit1+bit2+carry)%2;
carry=(bit1+bit2+carry)/2;
s.push(sum);
}
if(carry==1)
s.push(1);
return s;
}
void display(stack<int> &s)
{
cout<<”\n Sum= “;
while(!s.empty())
{
cout<<s.top();
s.pop();
} }