C Function Calls

C function calls

Created By: chatGPT

In C programming, a function is a block of code that performs a specific task. To use a function, you typically call it by its name and provide any required arguments. Here’s a simple example showing how to define a function and call it.

c
#include <stdio.h>

// Function definition
void greet() {
    printf("Hello, World!\n");
}

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

Functions can also accept parameters, which allow you to pass data to them. Here is an example of a function that takes two integers as arguments and returns their sum.

c
#include <stdio.h>

// Function that returns the sum of two numbers
int add(int a, int b) {
    return a + b;
}

int main() {
    int x = 5, y = 10;
    // Calling the add function
    int sum = add(x, y);
    printf("Sum: %d\n", sum);
    return 0;
}

You can also have functions that return values. The return type of a function must be specified in its definition. Here’s an example of a function that calculates the factorial of a number.

c
#include <stdio.h>

// Function to calculate factorial
int factorial(int n) {
    if (n <= 1) {
        return 1;
    }
    return n * factorial(n - 1);
}

int main() {
    int num = 5;
    // Calling the factorial function
    printf("Factorial of %d is %d\n", num, factorial(num));
    return 0;
}

Functions can be declared before they are defined. This practice improves code readability and allows for function calls to occur in any order. Here's how to declare a function prior to its definition.

c
#include <stdio.h>

// Function declaration
void displayMessage();

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

// Function definition
void displayMessage() {
    printf("This is a message from a function!\n");
}

In C, you can also pass parameters by reference using pointers. This is useful when you need a function to modify the original variable. Here’s an example demonstrating this concept via a function that swaps two numbers.

c
#include <stdio.h>

// Function to swap two numbers using pointers
void swap(int *x, int *y) {
    int temp = *x;
    *x = *y;
    *y = temp;
}

int main() {
    int a = 5, b = 10;
    // Calling the swap function
    swap(&a, &b);
    printf("After swapping: a = %d, b = %d\n", a, b);
    return 0;
}