C Function Definitions

C function definitions

Created By: chatGPT

In C, a function is a block of code that performs a specific task. Functions are used to modularize your code, making it more organized and reusable. A function is defined with a return type, name, and parameters (if any). Here’s the basic syntax of a function definition in C:

return_type function_name(parameter_list) {
    // function body
    // statements
    return value; // if return_type is not void
}

Let’s create a function that computes the area of a rectangle. The function will take two parameters: the length and the width of the rectangle, and it will return the calculated area.

float calculate_area(float length, float width) {
    return length * width;
}

Next, we can use this function in a main program. We'll declare the main function, call calculate_area, and display the result. Here's how this is done:

#include <stdio.h>

float calculate_area(float length, float width);

int main() {
    float length = 5.0;
    float width = 4.0;
    float area;
    area = calculate_area(length, width);
    printf("Area of the rectangle: %.2f\n", area);
    return 0;
}

float calculate_area(float length, float width) {
    return length * width;
}

In this example, we have:

Included the standard input-output library (stdio.h) for using printf.
Declared the calculate_area function above the main function to inform the compiler about it before use.
Called the calculate_area function inside main and stored the result in the variable area.
Printed the area with two decimal points using the printf function.

Functions can also return different types of values as per the requirement. If a function does not return a value, you should use the void return type. Here’s how you define a void function that simply prints a greeting.

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

You can call this function in your main program as well.

int main() {
    greet(); // Calling the greet function
    return 0;
}