Hello World in C — Your First C Program Explained (with printf)

Every C programmer’s journey begins with the same few lines: the “Hello, World!” program, which simply displays the text “Hello, World!” on the screen. It’s the traditional first program in any language — a quick way to confirm your setup works and to introduce the basic structure of a program. It’s also the starting point of our C programming tutorials series, and if you’re curious how it looks elsewhere, see our list of Hello World programs in 300 programming languages.

Table of Contents

• The Complete Program
• Line-by-Line Explanation
• Understanding the printf Function
• How to Compile and Run
• Common Errors Beginners Hit
• Variations to Try
• printf vs puts
• FAQ
• Next Steps

This guide walks through the C version line by line — explaining what each part does, how to compile and run it on Windows, Linux and macOS, the errors beginners hit most often, and a few variations to try next. Let’s take a look.

The Complete Program

#include <stdio.h>

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

When you compile and run this program, it prints:

Hello, World!

Line-by-Line Explanation

• #include <stdio.h> — This line tells the compiler to include the standard input/output library, which contains printf(). Without it, the program can’t print anything. Lines beginning with # are handled by the preprocessor before compilation.
• int main(void) — Every C program starts running from main() function. The int means it returns an integer to the operating system; void means it takes no input arguments.
• printf("Hello, World!\n"); — printf (“print formatted”) is the standard library function that writes text to the screen. The \n is an escape sequence that adds a newline so the next output starts on a fresh line. The semicolon ends the statement.
• return 0; — Returns 0 to the operating system, signalling that the program finished successfully. A non-zero value would indicate an error.

Understanding the printf Function

Because printf is the first function most C beginners meet, it’s worth understanding a little more. printf can do far more than print fixed text — it can format and insert values using format specifiers:

#include <stdio.h>

int main(void)
{
    int year = 2026;
    printf("Hello, World! It is %d.\n", year);
    return 0;
}

Here %d is replaced by the value of year. Common specifiers include %d (integer), %f (float), %c (character) and %s (string). You’ll use printf in almost every C program you write.

How to Compile and Run

Save your code in a file called hello.c, then compile and run it for your system:

If you don’t have a compiler yet, see our guide to the best C and C++ compilers or how to set up Turbo C on Windows 10/11.

Common Errors Beginners Hit

Variations to Try

Once the basic program works, try these small modifications to build confidence:

// Ask for the user's name, then greet them
#include <stdio.h>

int main(void)
{
    char name[50];
    printf("What is your name? ");
    scanf("%49s", name);
    printf("Hello, %s!\n", name);
    return 0;
}

// Print Hello, World! five times with a loop
#include <stdio.h>

int main(void)
{
    for (int i = 0; i < 5; i++)
        printf("Hello, World!\n");
    return 0;
}

printf vs puts

You can also print text with puts(), which automatically adds a newline:

#include <stdio.h>

int main(void)
{
    puts("Hello, World!");
    return 0;
}

Use puts() for simple lines of text and printf() when you need formatting or to insert values. (Note: always include return 0; and use int main(void) — the earlier int main(int argc, char** argv) form is for programs that read command-line arguments, which you don’t need yet.)

FAQ

Next Steps

Now that your first program runs, continue with:

1. Variables/Data Types in C
2. Operators in C
3. Control Flow in C
4. Functions in C