Variables in C++

Variables in Programming

In programming, a variable is a named storage location in memory that holds a particular type of data. Variables are stored either in the memory stack or heap, and different variable types differ mainly in the size of memory they occupy.

Example in C++

#include <iostream>  
   
int main() {  
    // int allows you to store values between approximately -2B to 2B  
    int variable = 8;  
    std::cout << variable << std::endl;  
  
    variable = 20;  
    std::cout << variable << std::endl;  
  
    std::cin.get();  
}  

Data Types and Their Sizes

• Int (“%d”): 32-bit integer
• Long (“%ld”): 64-bit integer
• Char (“%c”): Character type
• Float (“%f”): 32-bit real value
• Double (“%lf”): 64-bit real value

Data Type Sizes

• char: 1 byte (8 bits)
• short: 2 bytes (16 bits)
• int: 4 bytes (32 bits)
• long: 4 bytes (32 bits)
• long long: 8 bytes (64 bits)

These types can also be combined with unsigned to store only non-negative values.

Example of Floating Point Types

float var1 = 5.5f;  
double var2 = 5.2;  

Boolean Type

• bool: Can be true (1) or false (0). Although a boolean could be represented with a single bit, it takes up one byte due to memory addressability constraints.

sizeof(bool);  // Shows the size of the boolean type, which is 1 byte  

Pointers and References

In addition to basic data types, C++ supports pointers and references, which are used to store memory addresses and provide indirect access to other variables.