C Program To Find Sum of All Even Numbers Between Two Integers, using While loop

Lets write a C program to find sum of all the even numbers between range or between 2 integers input by the user.

Even Number: An even number is an integer that is exactly divisible by 2.

For Example: 10 % 2 == 0. When we divide 10 by 2, it give a reminder of 0. So number 10 is an even number.

Note: In this C program we ask the user to input start and end value. We assume that the user enters bigger value for variable end and smaller value for variable start. i.e., start < end

If user enters start = 10 and end = 20. C program finds all the even numbers between 10 and 20, including 10 and 20. So the even numbers are 10, 12, 14, 16, 18, 20. We add all these even numbers and output the sum to the console window. i.e., 10 + 12 + 14 + 16 + 18 + 20 = 90. We out put the value 90 as result.

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Video Tutorial: C Program To Find Sum of All Even Numbers Between Range, using While loop

Logic To Find Sum of All Even Numbers Between Two Integers, using While loop

Step 1: We ask the user to enter start and end value.

Step 2: We iterate through the while loop until value of start is less than or equal to value of variable end. Inside while loop we keep incrementing the value of variable start by one for each iteration.

Step 3: For every iteration we check if value present in variable start is a even number. i.e., start % 2 == 0. If this condition is true, then we add the value present in variable start to the previous value of variable sum.

Step 4: Once the control exits while loop, we print the value present in variable sum – which has the sum of all the even numbers between the range entered by the user.

Source Code: C Program To Find Sum of All Even Numbers Between Two Integers, using While loop

#include<stdio.h>
int main()
{
    int start, end, sum = 0;

    printf("Enter start and end value\n");
    scanf("%d%d", &start, &end);

    printf("\nSum of even no's from %d to %d is ", start, end);
    while(start <= end)
    {
        if(start % 2 == 0)
        {
            sum = sum + start;
        }
        start++;
    }
    printf("%d\n", sum);

    return 0;
}

Output 1:
Enter start and end value
10
20

Sum of even no’s from 10 to 20 is 90

Output 2:
Enter start and end value
25
50

Sum of even no’s from 25 to 50 is 494

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