# C++ Program to check if a number is even using Recursion

This program will read a number and check whether it is EVEN or ODD using recursion in C++.
Submitted by Abhishek Pathak, on April 09, 2017

There are various techniques of finding whether a number is even or not, the popular one being through the modulus operator. However, there is another method of finding it with the help of recursion.

## Program to check EVEN or ODD using Recursion in C++

﻿

```#include <iostream>
using namespace std;

//function prototype/declaration
int isEven(int);

int main()
{

int n;

cout<<"Enter a number: ";
cin>>n;

if(isEven(n))
cout<<"It is an EVEN Number";
else
cout<<"Is is an ODD Number";

cout<<endl;
return 0;
}

//function definition/body
int isEven(int n)
{
if(n == 0)
return 1;
else if(n == 1)
return 0;
else if(n<0)
return isEven(-n);
else
return isEven(n-2);
}
```

Output

```First run:
Enter a number: 101
Is is an ODD Number

Second run:
Enter a number: 120
It is an EVEN Number
```

In this program we are using the function recursion technique. We are recurring function until the value of n is either 1 or 0. If it ends at one of these values, the function returns 1 for even number and 0 for not even.

We have called the function inside of if statement. When the number is true, the function returns 1 and the result of if expression is true and similar is the case of non-even number.