C# - Data Types

One of the most important parts of learning any programming language is to understand what are the available data types, and how data is stored, accessed and manipulated in that language. Based on the data type of a variable, the operating system allocates memory to the variable and decides what can be stored in the reserved memory.

There are three types of data types in C# which are categorized below:

Value Data Types
Pointer Data Types
Reference Data Types

Value Data Types

The value data types store the value directly in the memory and it accept both signed and unsigned literals. There are two types of value data types in C# language:

Predefined Data Types - such as Integer, Boolean, Float, Double etc.
User defined Data Types - such as Structure, Enumerations, etc.

The below table describes the data types, size and it's range:

Data Type	Size	Range
bool	1 bytes	true or false
char	16 bit Unicode character	U+0000 to U+FFFF
sbyte	Signed 8-bit integer	-128 to 127
byte	Unsigned 8-bit integer	0 to 255
short	Signed 16-bit integer	-32,768 to 32,767
ushort	Unsigned 16-bit integer	0 to 65,535
int	Signed 32-bit integer	-2,147,483,648 to 2,147,483,647
uint	Unsigned 32-bit integer	0 to 4,294,967,295
long	Signed 64-bit integer	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
ulong	Unsigned 64-bit integer	0 to 18,446,744,073,709,551,615
float	4 bytes	±1.5 x 10^-45 to ±3.4 x 10³⁸, ~6-9 digits precision
double	8 bytes	±5.0 x 10^-324 to ±1.7 x 10³⁰⁸, ~15-17 digits precision
decimal	16 bytes	±1.0 x 10⁻²⁸ to ±7.9228 x 10²⁸, 28-29 digits precision

The memory size of a data type might be different as shown in the above table, depending upon platform. To find out the size of a data type, sizeof() function can be used.

using System;
 
class MyProgram {
  static void Main(string[] args) {
    Console.WriteLine("Size of float: {0} bytes", sizeof(float)); 
    Console.WriteLine("Size of int: {0} bytes", sizeof(int));
    Console.WriteLine("Size of char: {0} bytes", sizeof(char));
  }
}

The output of the above code will be:

Size of float: 4 bytes
Size of int: 4 bytes
Size of char: 2 bytes

Pointer Data Types

A pointer data type stores address of another variable. Pointers in C# have the same functionality as in C or C++. Syntax for declaring pointer is given below:

int *p1;     //pointer to an integer
float *p2;     //pointer to a float

//pointer p1 which stores address of Var
p1 = &Var;

Reference Data Types

The reference data types do not contain the actual data stored in a variable, but they contain a reference to the variables. With reference types, two variables can reference the same object. If the data is changed by one of the variables, the other variable automatically reflects this change in value. There are two types of reference data types in C# language:

Predefined Data Types - such as Object, String, Dynamic etc.
User defined Data Types - such as Class, Interface etc.