C++ Functions Tutorial

1. What is a Function?

A function is a block of code that performs a specific task. Functions help in code reusability and readability.

#include <iostream>
using namespace std;

// Function declaration
int add(int a, int b);

int main() {
    cout << "Sum: " << add(5, 3) << endl;
    return 0;
}

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

2. Function Declaration and Definition

Functions must be declared before they are used in a program. The syntax is:

return_type function_name(parameter_list);
                

The definition provides the implementation of the function.

3. Function Parameters

Functions can accept arguments. For example:

int multiply(int x, int y) {
    return x * y;
}
                

Call this function using multiply(4, 5).

4. Types of Functions

• Void Functions: These don't return a value.
• Inline Functions: Used for small, frequently called functions.
• Recursive Functions: Functions that call themselves.

5. Function Overloading

C++ allows multiple functions with the same name but different parameter lists:

#include <iostream>
using namespace std;

int add(int x, int y) {
    return x + y;
}

double add(double x, double y) {
    return x + y;
}

int main() {
    cout << "Int Sum: " << add(3, 4) << endl;
    cout << "Double Sum: " << add(2.5, 3.1) << endl;
    return 0;
}
                

6. Best Practices

• Use descriptive names for functions.
• Keep functions focused on a single task.
• Document complex logic within functions.