C program to print EVEN numbers from 1 to N using while loop

This is an example of while loop - In this C program, we are going to learn how can we print all EVEN numbers from given range (1 to N) using while loop?
Submitted by Manju Tomar, on March 09, 2018

Given a range (value of N) and we have to print all EVEN numbers from 1 to N using while loop.

Example

Input:
Enter value of N: 10

Output:
Even Numbers from 1 to 10:
2 4 6 8 10

Logic

There are two variables declared in the program 1) number as a loop counter and 2) n to store the limit.
Reading value of n by the user.
Initialising loop counter (number) by 1 as initial value number =1
Using while loop by checking the condition number<=n (value of number is less than or equal to n) - this will execute the loop until the value of number is less than or equal to n.
Then, within the loop, we are checking the condition to check whether number is EVEN or not, the condition is (number%2==0) - it returns true if number is divisible by 2.

Program to print EVEN numbers from 1 to N using while loop

#include <stdio.h>

int main()
{
	//loop counter declaration
	int number;
	//variable to store limit /N
	int n;

	//assign initial value 
	//from where we want to print the numbers
	number=1;

	//input value of N
	printf("Enter the value of N: ");
	scanf("%d",&n);

	//print statement
	printf("Even Numbers from 1 to %d:\n",n);

	//while loop, that will print numbers 
	while(number<=n)
	{
		//Here is the condition to check EVEN number
		if(number%2==0)
			printf("%d ",number);
		
		// increasing loop counter by 1
		number++;
	}

	return 0;
}

Output

Run(1)
Enter the value of N: 10 
Even Numbers from 1 to 10:
2 4 6 8 10 

Run(2)
Enter the value of N: 100 
Even Numbers from 1 to 100:
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 
32 34 36 38 40 42 44 46 48 50 52 54 56 58 
60 62 64 66 68 70 72 74 76 78 80 82 84 86 
88 90 92 94 96 98 100

Another way to print EVEN numbers from 1 to N

Since, we know that EVEN numbers starts from 2 and EVEN numbers are those numbers which are divisible by 2. So, we can run a loop from 2 to N by increasing the value of loop counter by 2.

Consider the given code...

//initialising the number by 2
number=2;
//print statement
printf("Even Numbers from 1 to %d:\n",n);

//while loop, that will print numbers 
while(number<=n)
{
	//print the number 
	printf("%d ",number);
	//increase the value of number by 2
	number+=2;
}