C++ Functions: Define and Call Examples

Introduction to C++ Functions

Functions in C++ are blocks of code designed to perform a specific task. They help organize code, make it reusable, and improve readability. In this guide, we’ll explore three diverse examples of C++ functions, showing how to define and call them effectively.

Example 1: Basic Addition Function

This example demonstrates how to define a simple function that adds two integers together. This function can be used in various applications, from calculators to data processing tasks.

To define the function, we specify the return type (int), the function name (add), and the parameters (two integers).

#include <iostream>
using namespace std;

// Function definition
int add(int a, int b) {
    return a + b;
}

int main() {
    int num1 = 5;
    int num2 = 3;
    // Function call
    int sum = add(num1, num2);
    cout << "The sum is: " << sum << endl;
    return 0;
}

In this code:

• The function add takes two integers as input and returns their sum.
• In the main function, we call add with num1 and num2 and store the result in sum, which is then printed out.

Notes

• You could modify this function to handle more than two numbers by using arrays or additional parameters.

Example 2: Function with Default Parameters

In this example, we will create a function that calculates the area of a rectangle. This function will have default parameters, allowing it to be called with one or two arguments.

#include <iostream>
using namespace std;

// Function definition with default parameters
float calculateArea(float length, float width = 1.0) {
    return length * width;
}

int main() {
    float length = 5.0;
    // Calling the function with one argument (width defaults to 1.0)
    float area1 = calculateArea(length);
    // Calling the function with both arguments
    float area2 = calculateArea(length, 3.0);
    cout << "Area with default width: " << area1 << endl;
    cout << "Area with specified width: " << area2 << endl;
    return 0;
}

In this code:

• The function calculateArea calculates the area of a rectangle, where width defaults to 1.0 if not provided.
• We demonstrate two calls: one using only the length (default width is used) and another specifying both length and width.

Notes

• Default parameters simplify function calls and make your functions more flexible.

Example 3: Function Returning a Value

This example illustrates how to create a function that checks whether a number is even or odd. It returns a boolean value, which can be useful in conditions and loops.

#include <iostream>
using namespace std;

// Function definition to check even or odd
bool isEven(int number) {
    return number % 2 == 0;
}

int main() {
    int num = 10;
    // Function call
    if (isEven(num)) {
        cout << num << " is even." << endl;
    } else {
        cout << num << " is odd." << endl;
    }
    return 0;
}

In this code:

• The function isEven checks if a number is even by using the modulus operator.
• In the main function, we call isEven and use its return value to determine whether to print that the number is even or odd.

Notes

• This function could be expanded to check for negative numbers or other conditions based on your needs.

By understanding these examples of C++ functions, you can start defining and calling functions in your own programs effectively, making your code cleaner and more efficient!