C Program: Calculate Sum of entered numbers with Do-While Loop

Last update on December 20 2024 13:16:20 (UTC/GMT +8 hours)

Write a C program that prompts the user to enter a series of numbers until they input a negative number. Calculate and print the sum of all entered numbers using a do-while loop.

Sample Solution:

C Code:

#include <stdio.h>

int main() {
    int num, sum = 0;  // Declare variables to store the entered number and the sum

    // Prompt the user to enter numbers until they input a negative number
    do {
        printf("Input a number (input a negative number to stop): ");
        scanf("%d", &num);  // Read the entered number

        if (num >= 0) {
            sum += num;  // Add the number to the sum if it's non-negative
        }

    } while (num >= 0);  // Continue the loop until the user enters a negative number

    // Print the sum of all entered numbers
    printf("Sum of entered numbers: %d\n", sum);

    return 0;  // Indicate successful program execution
}

Sample Output:

Input a number (input a negative number to stop): 2
Input a number (input a negative number to stop): 3
Input a number (input a negative number to stop): 0
Input a number (input a negative number to stop): 1
Input a number (input a negative number to stop): 56
Input a number (input a negative number to stop): 1
Input a number (input a negative number to stop): -12
Sum of entered numbers: 63

Explanation:

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

int num, sum = 0;: Declares two integer variables, 'num' to store the entered number, and 'sum' to store the sum of entered numbers. 'sum' is initialized to 0.
do {: Marks the beginning of a do-while loop. The code inside the loop will be executed at least once before checking the loop condition.
printf("Input a number (input a negative number to stop): ");: Displays a prompt asking the user to enter a number, with an additional instruction to enter a negative number to stop.
scanf("%d", &num);: Reads the entered number from the user and stores it in the variable 'num'.
if (num >= 0) {: Checks if the entered number is non-negative.
sum += num;: If the number is non-negative, it is added to the 'sum'.
} while (num >= 0);: Specifies the loop condition. The loop continues as long as the user enters a non-negative number.
printf("Sum of entered numbers: %d\n", sum);: Prints the sum of all entered numbers.
return 0;: Indicates successful program execution.
}: Marks the end of the "main()" function.

Flowchart:

C Programming Code Editor:

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