C++ Program to swap two numbers without third variable

We can swap two numbers without using third variable. There are two common ways to swap two numbers without using third variable:

1. By + and -
2. By * and /

Program 1: Using * and /

Let's see a simple C++ example to swap two numbers without using third variable.

#include <iostream>  
using namespace std;  
int main()  
{  
int a=5, b=10;      
cout<<"Before swap a= "<<a<<" b= "<<b<<endl;      
a=a*b; //a=50 (5*10)    
b=a/b; //b=5 (50/10)    
a=a/b; //a=10 (50/5)    
cout<<"After swap a= "<<a<<" b= "<<b<<endl;      
return 0;  
} 

Output:

Before swap a= 5 b= 10     
After swap a= 10 b= 5

Program 2: Using + and -

Let's see another example to swap two numbers using + and -.

#include <iostream>  
using namespace std;  
int main()  
{  
int a=5, b=10;      
cout<<"Before swap a= "<<a<<" b= "<<b<<endl;      
a=a+b; //a=15 (5+10)    
b=a-b; //b=5 (15-10)    
a=a-b; //a=10 (15-5)    
cout<<"After swap a= "<<a<<" b= "<<b<<endl;      
return 0;  
}  

Output:

Before swap a= 5 b= 10  
After swap a= 10 b= 5