🟡 Control Flow · Lesson 24

Recursion in C++

What is Recursion in C++?

Recursion in C++
Recursion occurs when a function calls itself. It needs a base case to stop and a recursive case to reduce the problem.

Level
🟡 Control Flow and Core Programming

Example File
recursion.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
base case	Base case used in Recursion in C++ programming.
recursive case	Recursive case used in Recursion in C++ programming.
stack	Stack used in Recursion in C++ programming.
factorial	Factorial used in Recursion in C++ programming.
call	Call used in Recursion in C++ programming.

Syntax / Pattern

function calls itself with smaller input.

Example Program

#include <iostream>
using namespace std;
int fact(int n){
    if(n == 0) return 1;
    return n * fact(n-1);
}
int main(){
    cout << fact(5);
    return 0;
}

Expected Output

120

Program Explanation

fact(5) becomes 5*fact(4).
Base case fact(0) returns 1.

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?

factorial
tree traversal
divide and conquer

Common Mistakes

Missing base case.
Using recursion where simple loop is better.

Practice Tasks

Write recursive sum of natural numbers.
Trace fact(4) step by step.

Summary

Recursion 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.