Writing, Compiling, and Running a C Program

1. What is a C Program?

A C program is a set of instructions written in the C programming language that tells the computer what to do. C is one of the oldest and most powerful programming languages. It's used in everything from mobile devices to operating systems.

Article Algo

2. Steps to Create and Run a C Program

To run a C program, follow these three main steps:

Step	Description	Tool Needed
1️⃣	Write the Code	Text Editor (VS Code, Notepad, etc.)
2️⃣	Compile the Code	C Compiler (like GCC)
3️⃣	Run the Program	Command Line / Terminal

Article Algo

✍️ Step 1: Writing a C Program

This is where you type your code into a text editor and save it with a .c extension.

✅ Basic Syntax of a C Program:


#include <stdio.h>  // Include input/output library


int main() {        // Start of main function

    printf("Hello, World!\n");  // Print message

    return 0;       // End of program

}

🧠 Explanation:

#include <stdio.h> – Tells the program to use the standard input-output library.
int main() – The starting point of any C program.
printf() – Prints text on the screen.
return 0; – Ends the program successfully.

📝 Save this file as: hello.c

Article Algo

⚙️ Step 2: Compiling the Program

The C code you wrote cannot be directly run by the computer. First, it must be converted (compiled) into a language the machine understands.

✅ Compilation Command (GCC):

gcc hello.c -o hello

📌 This command says:

Compile hello.c
Create an output file named hello (or hello.exe on Windows)

If there are no errors, this will create an executable file.

Article Algo

▶️ Step 3: Running the Program

Now that it's compiled, you can run the program to see the result.

✅ Run Command:

On Windows:

hello

On Linux/Mac:

./hello

🖨️ Output:

Hello, World!

🎉 Congratulations! You just ran your first C program.

Article Algo

📘 Example Program: Adding Two Numbers


#include <stdio.h>


int main() {

    int a = 5, b = 7;

    int sum = a + b;


    printf("Sum = %d\n", sum);

    return 0;

}

🖨️ Output:

Sum = 12

Article Algo

🧠 Quick Summary

C Programming Workflow
Task	What You Do
Write Code	Use a `.c` file and write in C language
Compile Code	Use `gcc filename.c -o outputname`
Run Program	Use `./outputname` or `outputname.exe`
See Output	Enjoy the result on the screen

Article Algo

Structure of a C Program Data Types in C Langauge