Write a C program to input a number from user and check whether given number is even or odd using functions. How to check even or odd using functions in C programming. Write a function in C programming to check even or odd.

**Example**

**Input**

Input any number: 10

**Output**

10 is even

## Required knowledge

Basic C programming, Functions, Returning value from function

## Declare function to find even odd

In my previous posts I have explained various ways to check even numbers. You can embed the logic to check even numbers using any of the following approaches in a function.

Must know - Program to check even number using conditional operator.

Let us define a function to check even or odd.

- First give a meaningful name to our function, say
`isEven()`

. - Next, the function must accept one integer which is to be validated for even condition, say
`isEven(int num)`

. - Finally as per name, the function must return
`true`

if given integer is even otherwise`false`

. However, C does not supports boolean values. In C programming, 0 is represented as`false`

and 1 (any non-zero integer) as`true`

. Hence,`isEven()`

we must return an integer from function.

So the function declaration to check even number is `int isEven(int num);`

## Program to check even or odd

```
/**
* C program to check even or odd using functions
*/
#include <stdio.h>
/**
* Function to check even or odd
* Returns 1 is num is even otherwise 0
*/
int isEven(int num)
{
return !(num & 1);
}
int main()
{
int num;
/* Input number from user */
printf("Enter any number: ");
scanf("%d", &num);
/* If isEven() function returns 0 then the number is even */
if(isEven(num))
{
printf("The number is even.");
}
else
{
printf("The number is odd.");
}
return 0;
}
```

In the above program I have used bitwise operator `&`

to check even or odd numbers. However you can also use if else statement to check even or odd numbers.

Output

Enter any number: 22 The number is even.

Happy coding 😉

### Recommended posts

- Function and recursion programming exercises index.
- C program to find maximum or minimum between two numbers using functions.
- C program to check prime, strong, armstrong or perfect numbers using functions.
- C program to count even and odd elements in array.
- C program to sort even and odd elements separately.
- C program to print even and odd numbers using recursion.

<pre><code> ----Your Source Code---- </code></pre>