C Program: Calculate sum of positive integers using while loop

C While Loop: Exercise-2 with Solution

Write a C program that prompts the user to input a series of integers until the user stops entering 0 using a while loop. Calculate and print the sum of all the positive integers entered.

Sample Solution:

C Code:

#include <stdio.h>

 int main() {
    int number;  // Variable to store the user input
    int sum = 0;  // Variable to store the sum of positive integers

    printf("Input integers (enter 0 to stop):\n");

    // Start a while loop to continue until the user enters 0
    while (1) {
        printf("Input a number: ");
        scanf("%d", &number);  // Read the user input

        if (number == 0) {
            break;  // Exit the loop if the user enters 0

        if (number > 0) {
            sum += number;  // Add positive numbers to the sum

    // Print the sum of positive integers
    printf("Sum of positive integers: %d\n", sum);

    return 0;  // Indicate successful program execution

Sample Output:

Input integers (enter 0 to stop):
Input a number: 5
Input a number: 9
Input a number: -3
Input a number: 2
Input a number: 5
Input a number: 6
Input a number: -20
Input a number: 0
Sum of positive integers: 27


Here are key parts of the above code step by step:

  • #include <stdio.h>: This line includes the standard input-output library, allowing functions like "printf()" and "scanf()".
  • int number;: Declares an integer variable 'number' to store the user input.
  • int sum = 0;: Declares an integer variable 'sum' and initializes it to 0. This variable will accumulate the sum of positive integers.
  • printf("Input integers (enter 0 to stop):\n");: Prints a message prompting the user to enter integers and telling them to input 0 to stop.
  • while (1) {: Starts an infinite "while" loop. The loop will continue until explicitly broken with the "break" statement.
  • printf("Input a number: ");: Prompts the user to enter a number.
  • scanf("%d", &number);: Reads the user input as an integer and stores it in the variable number.
  • if (number == 0) { break; }: Checks if the user entered 0. If true, it breaks out of the infinite loop.
  • if (number > 0) { sum += number; }: Checks if the entered number is positive. If true, it adds the number to the sum.
  • }: Closes the "while" loop.
  • printf("Sum of positive integers: %d\n", sum);: Prints the sum of positive integers entered by the user.
  • return 0;: Indicates that the program executed successfully and returns 0 to the operating system.
  • }: Closes the "main()" function.


Flowchart: C Program: Calculate sum of positive integers using while loop.

C Programming Code Editor:

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