INTRODUCTION TO PROGRAMMING & BASIC SYNTAX IN C#

4. Variables and Data Types

What are Variables?

Variables are named storage locations in memory that hold data which can be changed during program execution.

Common Data Types in C#

Data Type	Description	Example	Memory
int	Integer numbers	int age = 25;	4 bytes
double	Decimal numbers	double price = 19.99;	8 bytes
float	Decimal numbers (smaller)	float temperature = 98.6f;	4 bytes
char	Single character	char grade = 'A';	2 bytes
string	Text of any length	string name = "John";	varies
bool	True/False values	bool isActive = true;	1 bit

 

 Variable Declaration and Initialization

// Declaration only

int number;

// Declaration with initialization

string name = "Habiba";

double salary = 45000.50;

// Multiple variables of same type

int x = 5, y = 10, z = 15;

// Using var for implicit typing

var message = "Hello World"; // compiler infers string type

Constants
Variables that cannot change during program execution:

const double PI = 3.14159;

const int MAX_SCORE = 100;