# C Program to Check Whether a Number is Even or Odd

## The number is Even or Odd Program in C

We can determine whether a number is Even or Odd program in C. This can be tested using different methods. The test can be done using simple methods such as

• Testing the number’s divisibility by 2.
• If the remainder is zero, the number is even.
• If the remainder is not zero, then the number is odd.

The following algorithm describes how a C program can test if a number is even or odd.

```Example :

Number is 24
It is an even number because it is exactly divisible by 2
i.e 24 % 2 -> 0 (leaves no remainder on modulus/remainder operator)

Number is 15
It is odd number because it is not divisible by 2
i.e 15 % 2 ->1 (leaves 1 remainder on modulus/remainder operator) ``` Time Complexity O(1) Space Complexity O(1)

## Method 1

For user input number

• If number % 2 == 0
• If true then the number is even
• Else, the number has to odd

Here % is called as modulo/remainder operator

## Code

Run
```#include <stdio.h>

int main ()
{
int number;
printf ("Insert a number \n");
scanf ("%d", &number);

//Checking if the number is divisible by 2
if (number % 2 == 0)
printf ("Even");
else
printf ("Odd");

return 0;
}
```

### Output

`Insert a number10Even`

## Method 2

For this method, we use the ternary operator in C

For user input number

• If number % 2 == 0
• If true then the number is even
• Else, the number has to odd

Here % is called as modulo/remainder operator

## Code

Run
```#include <stdio.h>
int main ()
{
int number;
printf ("Insert a number \n");
scanf ("%d", &number);

//Checking if the number is divisible by 2
number % 2 == 0? printf ("Even"):printf ("Odd");

return 0;
}
```

### Output

`Insert a number15Odd`

## Method 3

For this method, we use the bitwise operator, in this case, bitwise and (&) How this works is below
• For any number following operation : (num & 1) will always result
• 1: If num is odd
• 0: if num is even
Let’s see how
```// 5 (in binary) : 00000101
// 1 (in binary) : 00000001

0 0 0 0 0 1 0 1

& 0 0 0 0 0 0 0 1

- - - - - - - - -

0 0 0 0 0 0 0 1
```

## Code

Run
```#include <stdio.h>

// Returns true if n is even, else odd
int isEven(int num)
{
// num & 1 is 1, then odd, else even
return (!(num & 1));
}

// Driver code
int main()
{
int num;
printf("Enter the number: ");
scanf("%d",&num);

isEven(num)? printf ("Even"):printf ("Odd");

return 0;
}

```

### Output

`Insert a number5Odd`

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