🟡 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	Recursion in C++ programming में Base case use होता है।
recursive case	Recursion in C++ programming में Recursive case use होता है।
stack	Recursion in C++ programming में Stack use होता है।
factorial	Recursion in C++ programming में Factorial use होता है।
call	Recursion in C++ programming में Call use होता है।

Syntax / Pattern

C++

function calls itself with smaller input.

Example Program

main.cpp

#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++ एक ज़रूरी C++ topic है। परिभाषा सीखें, syntax समझें, example program चलाएं और फिर practice tasks हल करके concept मज़बूत करें।

Recursion in C++ क्या है?

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

मुख्य फोकस
Concept + syntax + practical C++ program

इसे क्यों सीखें?

यह आपको सही और पढ़ने-योग्य C++ programs लिखने में मदद करता है।
यह school practicals, projects और competitive programming में बार-बार use होता है।
यह OOP, STL और data structures जैसे advanced topics की नींव बनाता है।

ज़रूरी Terms

Term	अर्थ / उपयोग
base case	Base case Recursion in C++ programming में use होता है।
recursive case	Recursive case Recursion in C++ programming में use होता है।
stack	Stack Recursion in C++ programming में use होता है।
factorial	Factorial Recursion in C++ programming में use होता है।
call	Call Recursion in C++ programming में use होता है।

Syntax / Pattern

C++

function calls itself with smaller input.

Example Program

main.cpp

#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

आम गलतियाँ (Common Mistakes)

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

अभ्यास (Practice Tasks)

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

सारांश

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