C# Variables and Types

C# is a strongly-typed language, which means every variable has a specific type.

Built-in Types

// Numeric types
int age = 25;
double price = 19.99;
decimal money = 100.50m;

// Text
string name = "John";
char grade = 'A';

// Boolean
bool isActive = true;

// Date and Time
DateTime now = DateTime.Now;

Type Conversion

Implicit Conversion

int num = 100;
long bigNum = num; // Automatically converts int to long

Explicit Conversion (Casting)

double pi = 3.14;
int rounded = (int)pi; // Explicitly convert double to int

var Keyword

C# can infer types using var:

var message = "Hello"; // Type is string
var number = 42;       // Type is int
var today = DateTime.Now; // Type is DateTime

Best Practices

  1. Choose appropriate types
  2. Use meaningful names
  3. Initialize variables
  4. Consider nullable types
  5. Use constants when values won’t change