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

## C Do-While Loop: Exercise-4 with Solution

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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