How to Write a C Program to Calculate the Sum of Two Numbers

In this comprehensive guide, we will walk you through the process of creating a simple C program to calculate the sum of two numbers. Along the way, we will cover the essential aspects of C programming such as variable declaration, user input, and output formatting. By the end of this article, you will have a solid understanding of how to write and compile a C program for this purpose.

Introduction to C Programming

C is a popular and versatile programming language that is widely used for system-level programming, embedded systems, and various applications. The language is often taught as a fundamentals course for computer science students and is still used in many industries. One of the simplest tasks in C programming is to write a program that performs basic arithmetic operations like adding two numbers.

Steps to Create the C Program

To create a C program for summing two numbers, you can follow these steps:

Step 1: Include Standard Input/Output Functions Header File

The first step in any C program is to include the stdio.h header file. This header file contains the necessary definitions and function prototypes for input and output operations.

#include ltstdio.hgt 

Step 2: Define the Main Function

The main function is the starting point of a C program. All statements in a C program execute from the main function. The function prototype of the main function is:

int main()

It returns an integer value and is the entry point of the program.

Step 3: Declare Variables for Number Input and Sum

Next, you need to declare variables to hold the two numbers and the sum of those numbers.

float num1, num2, sum;

In this example, we are using the float data type to allow for decimal numbers. If you only need to work with integers, you can use int instead.

Step 4: Prompt User for Input

You can use the printf function to display a prompt for the user:

printf("Enter the first number: ");

Use the scanf function to read the first number from the user and store it in the variable num1:

scanf("%f", num1);

Repeat the same process for the second number:

printf("Enter the second number: ");scanf("%f", num2);

Step 5: Calculate the Sum

Now, add the two numbers together and store the result in the sum variable:

sum  num1   num2;

Step 6: Display the Result

Finally, use the printf function to display the result of the addition:

printf("The sum of %f and %f is: %f
", num1, num2, sum);

Step 7: Return 0 from the Main Function

The main function should return 0 to indicate successful execution of the program:

return 0;

Complete C Program

Here is the complete C program that implements the above steps:

#include ltstdio.hgtint main() {    float num1, num2, sum;    printf("Enter the first number: ");    scanf("%f", num1);    printf("Enter the second number: ");    scanf("%f", num2);    sum  num1   num2;    printf("The sum of %f and %f is: %f
", num1, num2, sum);    return 0;}

gcc sum.c -o sum   # Compile the program./sum              # Run the executable