Introduction to Functions in C

Introduction to Functions in C

In C programming, a function is a reusable block of code that performs a specific task. Functions help you break down your program into smaller, manageable parts, improve readability, and allow code reuse.

Why Use Functions?

• Divide and conquer — break large problems into smaller tasks.
• Code reuse — write once, use many times.
• Improve readability and maintenance.

Syntax of a Function in C

return_type function_name(parameters) {
    // Code to execute
}

Example: Basic Function That Prints a Message

This function prints a simple greeting when called.

#include <stdio.h>

// Function declaration
void greet() {
    printf("Hello from a function!\n");
}

int main() {
    greet(); // Function call
    return 0;
}
  

Example: Function with Parameters

This function takes a name and prints a personalized greeting.

#include <stdio.h>

// Function with parameter
void greet(char name[]) {
    printf("Hello, %s!\n", name);
}

int main() {
    greet("Coder");
    return 0;
}
  

Example: Function That Returns a Value

Here we create a function that adds two numbers and returns the result.

#include <stdio.h>

// Function that returns a value
int add(int a, int b) {
    return a + b;
}

int main() {
    int sum = add(5, 3);
    printf("Sum is: %d\n", sum);
    return 0;
}
  

Function Structure in C

• Declaration: Tells the compiler about the function name and return type.
• Definition: Contains the actual code for the function.
• Call: Executes the function.

Recap

• void means the function doesn’t return a value.
• Functions can accept arguments and return results.
• Organize your code using functions for clarity and reuse.

Practice Time!

Try creating functions for tasks like checking even/odd numbers, calculating factorials, or converting units. Functions make your code modular and awesome!