🟡 Control Flow · Lesson 23

Functions in C++

What is Functions in C++?

Functions in C++
A function is a named block of reusable code. It makes programs modular, readable and easier to test.

Level
🟡 Control Flow and Core Programming

Example File
functions.cpp

Main Focus
Concept + syntax + practical C++ program

Why should you learn this?

It helps you write correct and readable C++ programs.
It is used repeatedly in school practicals, projects and competitive programming.
It builds the base for advanced topics such as OOP, STL and data structures.

Important Terms

Term	Meaning / Use
function	Function used in Functions in C++ programming.
parameter	Parameter used in Functions in C++ programming.
argument	Argument used in Functions in C++ programming.
return value	Return value used in Functions in C++ programming.
prototype	Prototype used in Functions in C++ programming.

Syntax / Pattern

return_type function_name(parameters) { statements; }

Example Program

#include <iostream>
using namespace std;
int square(int n){ return n*n; }
int main(){
    cout << square(6);
    return 0;
}

Expected Output

Program Explanation

square() receives 6 as argument.
It returns 6*6 to main().

Exam Tip: In C++ practical answers, write the logic first, then the program, then expected output. For theory, always include one suitable example.

Where will you use it?

calculator operations
validation
report generation

Common Mistakes

Forgetting return statement in non-void function.
Mismatch between declaration and definition.

Practice Tasks

Create a function for simple interest.
Create a function to check even number.

Summary

Functions in C++ is an important C++ topic. Learn the definition, understand the syntax, run the example program and then solve the practice tasks to make the concept strong.