🟢 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	Const used in Constants and Literals in C++ programming.
literal	Literal used in Constants and Literals in C++ programming.
macro	Macro used in Constants and Literals in C++ programming.
constexpr	Constexpr used in Constants and Literals in C++ programming.

Syntax / Pattern

const data_type NAME = value;

Example Program

#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++ 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.