🟢 Foundation · Lesson 11

Constants and Literals in C++

What is Constants and Literals in C++?

Constants and Literals in C++
Constants are values that should not change during program execution. Literals are fixed values written directly in code, such as 10, 3.14, "Hello" and true.

Level
🟢 Beginner – C++ Foundation

Example File
constants-literals.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
const	Constants and Literals in C++ programming में Const use होता है।
literal	Constants and Literals in C++ programming में Literal use होता है।
macro	Constants and Literals in C++ programming में Macro use होता है।
constexpr	Constants and Literals in C++ programming में Constexpr use होता है।

Syntax / Pattern

C++

const data_type NAME = value;

Example Program

main.cpp

#include <iostream>
using namespace std;

int main() {
    const double PI = 3.14159;
    double radius = 5;
    cout << "Area = " << PI * radius * radius;
    return 0;
}

Expected Output

Area = 78.5398

Program Explanation

PI is constant and cannot be changed later.
Literals 3.14159 and 5 are fixed values in the program.

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?

mathematical formulas
fixed tax rate
maximum marks

Common Mistakes

Trying to assign a new value to const variable.
Using magic numbers without names.

Practice Tasks

Create constants for MAX_MARKS and PASS_MARKS.
Write circle area program using const.

Summary

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