C Program: Calculate Sum of even and odd numbers (1-50) with Do-While Loops

Last update on July 30 2025 12:56:19 (UTC/GMT +8 hours)

3. Sum of Even and Odd Numbers

Write a C program that calculates the sum of even and odd numbers from 1 to 50 using do-while loops.

Sample Solution:

C Code:

#include <stdio.h>

int main() {
    int i = 1;  // Initialize loop control variable to 1
    int sumEven = 0;  // Initialize sum of even numbers
    int sumOdd = 0;   // Initialize sum of odd numbers

    // Calculate the sum of even and odd numbers from 1 to 50
    do {
        // Check if the current number is even
        if (i % 2 == 0) {
            sumEven += i;  // Add even number to the sumEven
        } else {
            sumOdd += i;   // Add odd number to the sumOdd
        }

        i++;  // Increment i for the next iteration

    } while (i <= 50);  // Continue the loop as long as i is less than or equal to 50

    // Print the sum of even and odd numbers
    printf("Sum of even numbers: %d\n", sumEven);
    printf("Sum of odd numbers: %d\n", sumOdd);

    return 0;  // Indicate successful program execution
}

Sample Output:

Sum of even numbers: 650
Sum of odd numbers: 625

Explanation:

Here is the break down of the above code step by step:

int i = 1;: Initializes the loop control variable i to 1.
int sumEven = 0;: Initializes the variable 'sumEven' to store the sum of even numbers.
int sumOdd = 0;: Initializes the variable 'sumOdd' to store the sum of odd numbers.
do {: Marks the beginning of the do-while loop. The code inside the loop will be executed at least once before checking the loop condition.
if (i % 2 == 0) {: Checks if the current value of 'i' is even.
sumEven += i;: If the current number is even, it is added to the 'sumEven'.
} else {: If the current number is not even (i.e., odd), this block is executed.
sumOdd += i;: Adds the odd number to the 'sumOdd'.
i++;: Increments the loop control variable for the next iteration.
} while (i <= 50);: Specifies the loop condition. The loop continues as long as 'i' is less than or equal to 50.
printf("Sum of even numbers: %d\n", sumEven);: Prints the sum of even numbers.
printf("Sum of odd numbers: %d\n", sumOdd);: Prints the sum of odd numbers.
return 0;: Indicates successful program execution.
}: Marks the end of the "main()" function.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to calculate the sum of only prime numbers from 1 to 50 using a do-while loop.
Write a C program to find the sum of all numbers from 1 to 50 that are divisible by both 3 and 5.
Write a C program to calculate the sum of even numbers from 1 to 50 but exclude numbers divisible by 4.
Write a C program to compute the sum of all odd numbers up to 50 while skipping every third odd number.

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