# C Program to Find the Sum of Three Numbers

In this article, we will write a C program to find the sum of three numbers.

The program takes three numbers from the user as input and prints their sum on the screen as output.

Sample Input:

``Enter three numbers: 10 20 30``

Output:

``Sum of the three numbers is: 60``

The following program shows how you can calculate the sum of three numbers in C programming:

```// C program to add three numbers
#include <stdio.h>

int main() {

int num1, num2, num3, res;

printf("Enter three numbers: ");
scanf("%d %d %d", & num1, & num2, & num3);

// Calculate the sum
res = num1 + num2 + num3;

// Print the result
printf("Sum of the three numbers is: %d", res);

return 0;

}```

Output:

```Enter three numbers: 10 20 30
Sum of the three numbers is: 60```

### Code Explanation:

• The program takes three numbers from the user and stores them in `num1`, `num2` and `num3` variables respectively.
• To store the sum of the three variables we have declared a variable `res`.
• The sum of the three numbers is calculated using the addition operator(`+`) and stored in the `res` variable.
• Finally, the sum of the three numbers is printed on the screen using the printf() function.

## Example 2: Find the Sum of Three Numbers using a Function

You can also define a function which takes three numbers as its arguments and returns their sum as a result.

See the implementation in the following program:

```// C program to add three numbers using function
#include <stdio.h>

//Function declaration

int main() {

int num1, num2, num3, res;

printf("Enter three numbers: ");
scanf("%d %d %d", & num1, & num2, & num3);

// Print the result
printf("Sum of the three numbers is: %d", res);

return 0;

}

// User defined function for addition
int add(int a, int b, int c) {
int result;
result = a + b + c;
return result;
}```

Output:

```Enter three numbers: 10 20 30
Sum of the three numbers is: 60```

### Code Explanation:

• The program takes three numbers from the user and stores them in `num1`, `num2` and `num3` variables.
• To get the sum of the three numbers, we have defined a function `add()`. The `add()` function takes three numbers as its arguments, calculates their sum and returns it.
• The sum returned by the `add()` method is stored in the `res` variable.
• Finally, the result is printed on the screen using the printf() function.