Variable Types

In C++, variables can be of various types, each serving different purposes and consuming different amounts of memory. Here's an overview of the standard variable types in C++:

Basic Data Types

Integer Types

• int: A standard integer type.
• short: A short integer, typically 2 bytes.
• long: A long integer, typically 4 or 8 bytes.
• long long: A long long integer, typically 8 bytes.

Example:

int age = 25;
short year = 2024;
long population = 7800000000;
long long distance = 123456789012345;

Floating-Point Types

• float: Single-precision floating-point.
• double: Double-precision floating-point.
• long double: Extended-precision floating-point.

Example

float height = 5.9f;
double pi = 3.141592653589793;
long double e = 2.718281828459045L;

Character Types

• char: Represents a single character, typically 1 byte.
• wchar_t: Represents a comprehensive character.

Example:

char initial = 'A';
wchar_t wideChar = L'Ω';

Boolean Type

• bool: Represents a boolean value, true or false.

Example:

bool isStudent = true;

Derived Data Types

Arrays

• A collection of elements of the same type.

int numbers[5] = {1, 2, 3, 4, 5};

Pointers

• Variables that store memory addresses of other variables.

Example:

int x = 10;
int* ptr = &x;

References

• An alias for another variable.

Example:

int y = 20;
int& ref = y;

Enumerations

• A user-defined type consisting of a set of named integral constants.

Example:

enum Color { RED, GREEN, BLUE };
Color myColor = GREEN;

User-Defined Types

Structures

• A collection of variables of different types.

struct Person {
   int age;
   float height;
   char initial;
};
Person john = {25, 5.9, 'J'};

Unions

• Like structures, it can store only one of its non-static data members at a time.

Example:

union Data {
   int i;
   float f;
   char str[20];
};
Data data;
data.i = 10;

Classes

• Similar to structures but with access control and other OOP features.

Example:

class Car {
public:
   int speed;
   void setSpeed(int s) {
       speed = s;
   }
};
Car myCar;
myCar.setSpeed(100);

Example Code

Here's a complete example demonstrating different variable types in C++:

#include <iostream>
using namespace std;
// Enumeration type
enum Color { RED, GREEN, BLUE };
// Structure type
struct Person {
   int age;
   float height;
   char initial;
};
// Union type
union Data {
   int i;
   float f;
   char str[20];
};
// Class type
class Car {
public:
   int speed;
   void setSpeed(int s) {
       speed = s;
   }
};
int main() {
   // Basic data types
   int age = 25;
   float height = 5.9f;
   char initial = 'J';
   bool isStudent = true;
   // Derived data types
   int numbers[5] = {1, 2, 3, 4, 5};
   int* ptr = &age;
   int& ref = age;
   
   // Enumeration
   Color myColor = GREEN;
   // Structure
   Person john = {25, 5.9, 'J'};
   // Union
   Data data;
   data.i = 10;
   // Class
   Car myCar;
   myCar.setSpeed(100);
   // Output values
   cout << "Age: " << age << endl;
   cout << "Height: " << height << endl;
   cout << "Initial: " << initial << endl;
   cout << "Is student: " << boolalpha << isStudent << endl;
   cout << "Numbers: ";
   for (int i = 0; i < 5; i++) {
       cout << numbers[i] << " ";
   }
   cout << endl;
   cout << "Pointer to age: " << *ptr << endl;
   cout << "Reference to age: " << ref << endl;
   cout << "Color: " << myColor << endl;
   cout << "John's age: " << john.age << endl;
   cout << "John's height: " << john.height << endl;
   cout << "John's initial: " << john.initial << endl;
   cout << "Union data (int): " << data.i << endl;
   cout << "Car speed: " << myCar.speed << endl;
   return 0;
}

This code provides a comprehensive overview of variable types in C++ and demonstrates their usage.