🔵 Core C++ · Lesson 31

Default Arguments

What is Default Arguments?

Default Arguments
Default arguments allow a function parameter to have a value when the caller does not provide it.

Level
🔵 Core C++ Features

Example File
default-arguments.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
default value	Default Arguments programming में Default value use होता है।
parameter	Default Arguments programming में Parameter use होता है।
function call	Default Arguments programming में Function call use होता है।
optional argument	Default Arguments programming में Optional argument use होता है।

Syntax / Pattern

C++

void show(int x = 10);

Example Program

main.cpp

#include <iostream>
using namespace std;
void greet(string name = "Student"){
    cout << "Hello " << name;
}
int main(){
    greet();
    return 0;
}

Expected Output

Hello Student

Program Explanation

No argument is passed, so default value Student is used.

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?

optional settings
report formatting
menu defaults

Common Mistakes

Putting default argument before non-default argument.
Repeating defaults in both declaration and definition incorrectly.

Practice Tasks

Create function bill(price, tax=18).
Call same function with and without argument.

Summary

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