Header files and include directive - Mini Project: Build & Apply

Header files and include directive

📖 Scenario: You are creating a simple C program that uses a header file to organize your code. This helps keep your program clean and easy to manage.

🎯 Goal: You will create a header file with a function declaration, include it in your main C file using the #include directive, and call the function to display a greeting message.

📋 What You'll Learn

Create a header file named greetings.h with a function declaration for void say_hello();

Create a C source file named main.c that includes greetings.h using the #include directive

Define the function say_hello in main.c to print Hello, welcome to C programming!

Call the say_hello function from main to display the message

💡 Why This Matters

🌍 Real World

Header files help organize code in large C projects by separating declarations from definitions.

💼 Career

Understanding header files and the include directive is essential for C programming jobs, especially in systems programming and embedded development.

1

Create the header file with function declaration

Create a header file named greetings.h that contains the function declaration void say_hello();

C

// greetings.h
// Declare the function say_hello
// Your code here

Need a hint?

Use void say_hello(); to declare the function inside the header guards.

2

Include the header file in main.c

Create a C source file named main.c and include the header file greetings.h using the #include "greetings.h" directive at the top.

C

#include "greetings.h"

// Your code here

Need a hint?

Use #include "greetings.h" with quotes to include your own header file.

3

Define the say_hello function

In main.c, define the function say_hello that prints Hello, welcome to C programming! using printf. Remember to include <stdio.h>.

C

#include 

#include "greetings.h"

// Define say_hello function here

int main() {
    // Your code here
    return 0;
}

Need a hint?

Define void say_hello() and use printf to print the message with a newline.

4

Call say_hello from main and print output

In main, call the function say_hello() to display the greeting message. Then compile and run the program to see the output.

C

#include 

#include "greetings.h"

void say_hello() {
    printf("Hello, welcome to C programming!\n");
}

int main() {
    say_hello();
    // Your code here
    return 0;
}

Need a hint?

Call say_hello(); inside main to print the greeting.