Programming And Technical Tutorials: C# Data Types Tutorial For Beginners With Examples

In C# every variable and constant has a type. The types can be categorized as below:

Value types
Reference types
Pointer types

Before proceeding further lets briefly discuss about C# variables and constants.

Variables:

A variable represents a location in the system's memory. Using the variable a .NET program can access that specific memory location.

Constants:

A constant represents a fixed value which cannot be changed throughout the life of a program.

C# Value Types

A value type variable contains data directly. So, when a value type data is copied the actual data gets copied to a different location.

In .NET all value types derive directly from System.Valuetype class and System.Valuetype class derives from System.Object class. System.Object is the base type for all Types.

Below is the list of built-in value types:

Data Type	Symbolizes	Range	.NET Type
bool	Boolean value	True or False	System.Boolean
byte	Unsigned 8-bit integer	0 to 255	System.Byte
char	Unicode 16-bit character	U+0000 to U+ffff	System.Char
decimal	128-bit data type	±1.0 x 10^-28 to ±7.9 x 10²⁸	System.Decimal
double	64-bit floating point value	±5.0 x 10^-324 to ±1.7 x 10³⁰⁸	System.Double
float	32-bit floating point value	±1.5 × 10⁻⁴⁵ to ±3.4 × 10³⁸	System.Single
int	Signed 32-bit integer	-2,147,483,648 to 2,147,483,647	System.Int32
long	Signed 64-bit integer	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807	System.Int64
sbyte	Signed 8-bit integer	-128 to 127	System.SByte
short	Signed 16-bit integer	-32,768 to 32,767	System.Int16
uint	Unsigned 32-bit integer	0 to 4,294,967,295	System.UInt32
ulong	System.UInt64	0 to 18,446,744,073,709,551,615	Unsigned 64-bit integer
ushort	System.UInt16	0 to 65,535	Unsigned 16-bit integer

The above types are know as simple types and are available in .NET Framework's Common Type System (CTS).

The floating point types, decimal types and integral types are also called as numeric types. The numeric types are categorized in the below table:

Numeric Type	Data Type
Floating point type	float
Floating point type	double
Decimal type	decimal
Integral type	sbyte
	byte
	char
	short
	ushort
	int
	uint
	long
	ulong

Apart from these built-in value types developers can create their own user-defined value types using the struct and enum keywords.

Visit Structs and Enums chapters to read about these data types in detail.

Structs:

A struct type is usually used for small groups of related variables. It is suitable for representing light weight objects such as Point, Rectangle, Color etc. struct keyword is used to declare a struct type.

In the below example we have created a new user-defined value type called as Square. Like int, bool etc. we can now declare a variable of type Square.

Example:

using System;
public struct Square 
{
    public int x, y;

    public Square(int p1, int p2) 
    {
        x = p1;
        y = p2;    
    }
}

Enums:

An enum type consists of a set of named constants called as the enumerator list.enum keyword is used to declare an enum type.

In the below example we have created a new user-defined value type called as Status. Like all other types we can declare variables of type Status.

Example:

using System;
enum Status {
    None, 
    Started, 
    In Progress, 
    Complete
};

C# Reference Types

A reference type variable contains address of the memory area where the actual data is stored. So, unlike value type variables, the reference type variable do not contain data directly but reference to the actual data.

Reference types are also called as objects. They derive directly from System.Object.

Below is the list of built-in reference types available in C#:

Object type
Dynamic type
String type

Object type

In .NET Framework the object type is an alias for System.Object class. As mentioned earlier System.Object is the base class of all the classes in .NET Framework. It is the ultimate starting point of the class hierarchy.

A variable of type object can be assigned any type of data. Which means integers, decimals, enums, strings etc can all be assigned to a object type variable.

Example:

class Program
{
    static void Main(string[] args)
    {
        object objRefType = "a";
        object objValType = 1;
            
        System.Console.WriteLine(objRefType.GetType());
        System.Console.WriteLine(objValType.GetType());

        System.Console.ReadLine();
    }
}

Output of the above program will be
System.String
System.Int32

Dynamic type

The dynamic type variables can store any type of data. The type checking for dynamic types are done only during run time.

In most cases dynamic types behaves like object types except that the type checking of object type is done at the compile time whereas the type checking of dynamic type is done at runtime.

Example:

class Program
{
    static void Main(string[] args)
    {
        dynamic dyn = 20;
        System.Console.WriteLine(dyn.GetType());     
    }
}

Output of the above program will be System.Int32

String type

In .NET Framework the string type is an alias for System.String class. A string type variable can be assigned any string data. A string data is always enclosed within double quotes.

Remember, unlike dynamic or object types you cannot assign any other types like int, float, struct etc. to string type. Doing so will result in an error.

Example:

class Program
{
    static void Main(string[] args)
    {
        string planetName = "Earth";
        System.Console.WriteLine(planetName.GetType());     
    }
}

Output of the above program will be System.String

Visit String types chapter to learn more about this type in detail.

Apart from these built-in reference types developers can create their own user-defined reference types using the class, interface and delegate keywords. We will cover these in subsequent chapters.

C# Pointer Types

Pointer type variable contains address of another variable. By default C# does not supports pointer types. However, using the unsafe keyword in C# we can create pointer types.

Pointer types do not inherit from object type and these types cannot be converted to object types or vice-versa.

Pointer type variables are created using the * symbol in front of the type. In the below example ipointer is a pointer type variable and holds address of integer variable actualValue.

Example:

class Program
{
    unsafe static void Main(string[] args)
    {
        int* ipointer;

        int actualValue = 10;

        ipointer = &actualValue;

        System.Console.WriteLine(*ipointer);            
        System.Console.ReadLine();
    }
}

Output of the above program will be 10

C# Data Types Tutorial For Beginners With Examples

C# Value Types

Structs:

Enums:

C# Reference Types

Object type

Dynamic type

String type

C# Pointer Types

Computer Programming News -- ScienceDaily