# Functions Exercises

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.

**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.

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: 36

The number is even.