🟢 Foundation · Lesson 07

Variables and Data Types in C++

What is Variables and Data Types in C++?

Variables and Data Types in C++
A variable is a named memory location used to store data. Data type tells the compiler what kind of value will be stored and how much memory may be needed.

Level
🟢 Beginner – C++ Foundation

Example File
variables-data-types.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
int	Variables and Data Types in C++ programming में Int use होता है।
float	Variables and Data Types in C++ programming में Float use होता है।
double	Variables and Data Types in C++ programming में Double use होता है।
char	Variables and Data Types in C++ programming में Char use होता है।
bool	Variables and Data Types in C++ programming में Bool use होता है।
string	Variables and Data Types in C++ programming में String use होता है।

Syntax / Pattern

C++

data_type variable_name = value;

Example Program

main.cpp

#include <iostream>
using namespace std;

int main() {
    int age = 16;
    double percentage = 92.5;
    char grade = 'A';
    bool passed = true;

    cout << age << " " << percentage << " " << grade << " " << passed;
    return 0;
}

Expected Output

16 92.5 A 1

Program Explanation

bool true is printed as 1 by default.
double stores decimal values with better precision than float.
char stores a single character.

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?

student records
fee calculation
marks and percentage
conditions

Common Mistakes

Using int for decimal values.
Using single quotes for full strings.
Using invalid variable names with spaces.

Practice Tasks

Create variables for roll number, name, marks and grade.
Print size of different data types using sizeof().

Summary

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