C# Data Type

In C#, data types define the kind of values a variable can hold and how much memory it uses. Since C# is a strongly typed language, every variable must have a specific type declared before it is used. Understanding data types is one of the most important steps in learning C#.

Categories of Data Types in C

C# data types are divided into several categories:

1. Value Types

2. Reference Types

3. Pointer Types (used in unsafe code)

For beginners, the most important categories are value types and reference types.

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Value Types

Value types store the actual data directly in memory. When you assign one value type to another, the value is copied.

Examples of value types in C#:

• int → Stores whole numbers. Example: 10

• double → Stores double-precision floating point numbers. Example: 3.14

• float → Stores single-precision floating point numbers. Example: 2.5f

• decimal → Stores high-precision decimal numbers, useful for financial calculations. Example: 19.99m

• char → Stores a single character. Example: 'A'

• bool → Stores true or false values. Example: true

• byte → Stores unsigned 8-bit numbers (0 to 255). Example: 200

• short → Stores 16-bit integers. Example: -32768 to 32767

• long → Stores 64-bit integers. Example: 9223372036854775807

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Reference Types

Reference types store a reference (or address) to the actual data, not the data itself. When assigning one reference type variable to another, both refer to the same memory location.

Examples of reference types:

• string → Stores text. Example: "Hello, World!"

• object → The base type from which all other types derive.

• arrays → A collection of elements of the same type. Example: numbers = {1, 2, 3, 4}

• classes → User-defined types that represent objects with fields and methods.

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Null Value

Reference types can be null, meaning they do not point to any object. Value types normally cannot be null, but you can make them nullable by adding a question mark. Example: int? number = null

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Type Conversion

Sometimes, you need to convert one data type into another. C# provides two ways:

1. Implicit Conversion (safe, automatic)
   Example: int x = 10; double y = x;

2. Explicit Conversion (requires casting)
   Example: double a = 9.8; int b = (int)a;

C# also provides helper methods like Convert.ToInt32() or int.Parse() for conversions.

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Default Values

Every data type in C# has a default value when not explicitly assigned:

• int → 0

• double → 0.0

• bool → false

• string → null

• object → null