Your First C Program

Congratulations! 🎉

In the previous lessons, you learned about the history of C, installed the compiler, and understood the structure of a C program.

Now it's time to write your first C program and execute it successfully.

This is the beginning of your programming journey.

🎯 Learning Objectives

After completing this lesson, you will be able to:

• Write your first C program.
• Understand every line of code.
• Compile and execute a C program.
• Display output using printf().
• Understand the role of the main() function.
• Identify common beginner mistakes.

📖 What is a C Program?

A C program is a collection of instructions written using the C programming language.

These instructions tell the computer exactly what to do.

Every C program must follow a proper structure and contain a main() function.

💻 Hello World Program

cCopy
#include <stdio.h>

int main()
{
    printf("Hello, World!");

    return 0;
}

▶ Output

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Hello, World!

🔍 Understanding Every Line

Line 1

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#include <stdio.h>

This includes the Standard Input Output library.

Without it, the compiler doesn't know what printf() is.

Line 2

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int main()

Every C program starts from the main() function.

Execution begins here.

Line 3

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{

Opening brace.

Marks the beginning of the function.

Line 4

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printf("Hello, World!");

Displays text on the screen.

printf() means Print Formatted.

Line 5

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return 0;

Returns control back to the operating system.

0 means successful execution.

Line 6

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}

Closing brace.

Marks the end of the function.

🖥 Program Execution

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Source Code
      │
      ▼
Compiler
      │
      ▼
Machine Code
      │
      ▼
Execution
      │
      ▼
Output

📝 Writing Your First Program in VS Code

Step 1

Create a folder

C Programs

Step 2

Create

hello.c

Step 3

Paste the code.

Step 4

Save the file.

Step 5

Compile

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gcc hello.c -o hello

Step 6

Run

Windows

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hello

Linux/macOS

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./hello

Expected Output

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Hello, World!

🎨 Customizing the Program

Instead of printing "Hello World",

try

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#include <stdio.h>

int main()
{
    printf("Welcome to KAURA Learning Hub!");

    return 0;
}

Output

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Welcome to KAURA Learning Hub!

Another Example

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#include <stdio.h>

int main()
{
    printf("My Name is Kaushal");

    return 0;
}

Output

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My Name is Rahul

Printing Multiple Lines

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#include <stdio.h>

int main()
{
    printf("Welcome\n");

    printf("To\n");

    printf("KAURA");

    return 0;
}

Output

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Welcome
To
KAURA

Escape Sequences

Compilation Process

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hello.c
     │
     ▼
 GCC Compiler
     │
     ▼
 hello.exe
     │
     ▼
 Output

Common Errors

Missing Semicolon

❌

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printf("Hello")

✅

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printf("Hello");

Missing Header File

❌

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int main()
{
    printf("Hello");
}

✅

cCopy
#include <stdio.h>

Wrong Main Function

❌

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main()

✅

cCopy
int main()

Missing Curly Braces

Always write

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{
}

💡 Best Practices

• Save before compiling.
• Indent your code.
• Use meaningful messages.
• Keep one statement per line.
• Read compiler errors carefully.

🌍 Real World Analogy

Imagine giving instructions to a robot.

Every instruction must be written correctly.

If one instruction is wrong,

the robot stops working.

Programming works exactly the same way.

🧠 Interview Questions

1. What is the first program in C?
2. Why do we use printf()?
3. What is the purpose of return 0;?
4. Why is main() mandatory?
5. What is stdio.h?

✍ Practice Questions

1. Print your name.
2. Print your college name.
3. Print your city.
4. Print three lines using \n.
5. Modify the Hello World program.

📚 Lesson Summary

You learned:

• How to write your first C program.
• The purpose of every line.
• How to compile and run programs.
• Escape sequences.
• Common errors.
• Best coding practices.

You have now officially written and executed your first C program!

🚀 What's Next?

In the next lesson, Variables in C, you'll learn how computers store data using variables, how to declare them, initialize them, and use them in real programs.

Happy Coding with KauraX 💙