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C 📅 July 1, 2026 ⏱ 5 min read

C Program to Write Hello World - Full Code and Output

Vansh Kapoor
Vansh Kapoor
Founder
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C Program to Write Hello World - Full Code and Output

There's a moment every C programmer remembers — writing their first program to print 'Hello, World!'. It's a simple program, but it opens the door to understanding how C works. Here’s how our program looks and what it does.

Prerequisites for Writing the Hello World Program in C

Before you write your first 'Hello, World!' program in C, make sure you have:

  • A basic understanding of C syntax, especially the int main() function.
  • The C Standard Input and Output library included: <stdio.h>.
  • Any C compiler such as GCC 9 or newer — or just run it in the EduSeekho online compiler.

Source Code of C Program to Write Hello World

Below is the code to display 'Hello, World!' in the C programming language. It's short and simple.

hello_world.cC▶ Run
// A simple C program to print Hello, World!
#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

Try this code yourself — free

Run it in the EduSeekho online compiler. No setup needed.

▶ Open Compiler

Output of the Hello World Program

When you run this program, it will simply display:

OutputText▶ Run
Hello, World!
Output of C Program to Write Hello World
Output of C Program to Write Hello World

Algorithm to Write Hello World in C

To print 'Hello, World!' in C, these are the steps the program follows:

  1. Include the C Standard Input and Output library with <stdio.h>.
  2. Define the main() function which is the entry point of the program.
  3. Use the printf() function to output "Hello, World!".
  4. Return 0 to indicate successful execution.
flowchart TD
  A([Start]) --> B[Include stdio.h]
  B --> C[Define main function]
  C --> D{Print Hello, World?}
  D -->|Yes| E[/Print "Hello, World!"/]
  E --> F([End])
Flowchart: the algorithm step by step

How the C Program to Write Hello World Works

Let's break down what each line in this program does:

  • #include <stdio.h> - This line includes the standard input-output library, which allows us to use printf().
  • int main() - This is the main function where the execution starts.
  • printf("Hello, World!\n") - The printf function is used to print text to the screen. Here, it prints 'Hello, World!'.
  • return 0; - This line ends the main function and returns a value of 0 to the operating system, indicating that the program executed successfully.
🧠

Quick Quiz — test your understanding

Tap an option to check your answer

What library is necessary to use the printf function in a C program?

🎉Correct! The printf function is part of the stdio.h library.
🤔Not quite. Think about libraries related to input and output.

Time and Space Complexity of the C Program to Write Hello World

Analyzing the complexity of this simple program can still be insightful.

Time Complexity: O(1). The program runs a fixed number of steps regardless of the input, specifically just printing a line with printf(). This means the time taken does not increase with input size or any external factor.

Space Complexity: O(1). The program uses a fixed amount of memory for the execution because it's only storing minimal data such as the return type of main() and the output string in printf(). No other variables are defined.

⚠️

Common mistake: If you forget to include <stdio.h>, you'll hit a compilation error since printf won't be recognized.

Key takeaway: The 'Hello, World!' program is a rite of passage that introduces you to the structure of a C program. It's small but powerful in its simplicity.

FAQs About C Program to Write Hello World

Here are some questions beginners often ask when creating a 'Hello, World!' program in C.

It includes the Standard Input Output library in your program, which gives you the printf() function.
This marks the main function where execution starts. It's mandatory in every C program.
It shows that the program ran successfully. Just a way to tell the OS it’s done.
Yeah, puts() can display text too, but it’s not as flexible as printf().
In C, you usually use int main() to show you're returning an integer, which is what most C compilers expect.
If you leave it out, the program might still work, but it’s good practice and sometimes needed to tell the OS it finished successfully.
Semicolons end statements. They mark the close of one logical expression.

If you found this program helpful, check out these related programs:

Conclusion

This 'Hello, World!' program might be the first step, but it lays the foundation for more complex programming journeys. Try extending it by learning how to accept user input next. Keep practicing, and you'll soon be exploring more advanced C programming territory.

Test your skills with our C quiz and start coding right away with our online C compiler.