C# Data Types

The data type tells a C# compiler what kind of value a variable can hold. Data type defines the type of data entered by the user. In C#, data types are categorized into 3 categories:

Value Type

Reference Type

Object Type

Value Type

A data type is a value type if it holds a data value directly. For example: int i=10;. They are derived from the class System.ValueType. Value type again categorized into 3 main categories:

Integer Data Type

Floating-point Data Type

Character Data Type

Integer Data Type

Integer Data Type contains only numbers. Decimal numbers are not allowed. Integer data type is further classified into different categories listed in the below table:

Type	Aliased	Signed/Unsigned	Suffix	Size	Range
sbyte	System.SByte	Signed	None	1 byte	-128 to 127
byte	System.Byte	Unsigned	None	1 byte	0 to 255
short	System.Int16	Signed	None	2 bytes	-32768 to 32767
ushort	System.UInt16	Unsigned	None	2 bytes	0 to 65535
int	System.Int32	Signed	None	4 bytes	-2147483648 to 2147483647
uint	System.UInt32	Unsigned	U or u	4 bytes	0 to 4294967295
long	System.Int64	Signed	L or l	8 bytes	-2⁶³ to 2⁶³-1
ulong	System.UInt64	Unsigned	Ul,UL,ul, LU,lU,Lu	8 bytes	0 to 2⁶⁴-1

Floating-point Data Type

Floating-point data types are used to store decimal values. Floating point is further classified into different categories.

Type	Aliased	Suffix	Size	Range
float /single	System.Single	F or f	4 byte	1.5 x 10^-45 to 3.4 x 10³⁸ with precision of 7 digits
Double	System.Double	None, d or D	8 byte	5.0 x 10^-324 to 1.7 x 10³⁰⁸ with precision of 15-16 digits
Decimal	System.Decimal	M or m	16 bytes	1.0 x 10^-28 to 7.9 x 10²⁸ with precision of 28-29 digits

Character Data Type

Character Data Type is used to store alphabet, number, special character.

Type	Aliased	Suffix	Allowed Values
Char	System.Char	None	Single Unicode character, stored as integer between 0 to 65535
Bool	System.Boolean	None	Boolean values, true or false, Default value is false.
DateTime	System.DateTime	8 bytes	0:00:00am 1/1/01 to 11:59:59pm 12/31/9999

Reference Type

Unlike value types, a reference type doesn't store its value directly. Instead, it stores the address where the value is being stored. For example: string s = "Hello World"; Reference types have a null value by default, when they are not initialized.

Type	Aliased	Suffix	Allowed Values
String	System.String	None	A sequence of characters
Arrays		None	Collection of values
Class		None
Delegates		None

Object Type

The Object Type is the base class for all data types. In object data types any type of value can be assigned.

GetType(): It returns the Type object of current instance.
object obj1 = 4;
object obj2 = "Test";
string type1 = obj1.GetType().ToString(); // returns System.Int32
string type2 = obj2.GetType().ToString(); // returns System.String.

Comparing Value type and Reference type
S.No.	Value type	Reference type
	Value type stores the value of their data.	Reference types store the address of their data.
	In value type, creating new objects occupy the different memory location.	In Reference type, creating a new object does not occupy a new memory location rather it shares the same memory location of existing objects.
	In value type change in one object does not reflect other object.	In Reference type, change of value in one object reflects another object.