C # Data Type

I. Value Type and reference type

1. Value Type:

Storage location: stored in the memory Stack

Including: simple type (INT, double, float, etc)

Structure Type (struct types)

Enumeration type (enmu types)

2. Reference Type:

Storage location: stored in the memory heap

Including: Class, interface, array, string

 

3. Value Type and reference type

Features	Value Type	Reference Type
Storage location	Stack	Heap
Default Value	0	Null
Parameters passed to the Method	Copy Value	Reference
Variable Storage	Actual value	Reference address

 

4. packing and unpacking

Packing: The value type is automatically converted to the reference type.

Example: int num = 200;

Object OBJ = num;

 

Binning: converts a reference type to a value type.

Example: object OBJ = 200;

Int num = (INT) OBJ;

 

Disadvantages of packing: it consumes more time than unpacking

Note: Do not pack or unpack the box at will in the program.

 

 

Ii. enumeration: belongs to the value type and is used to define a group of constants.

 

1. Definition restrictions: you cannot define your own methods, implement interfaces, or define attributes or indexes.

2. Statement:

Statement Syntax:

Access modifier Enum name

{

Enumeration member

}

Note: Members are separated by commas (,).

Example: Public Enum sex

{

Boy,

Girl

}

3. Usage:

Use Cases:

A) defines static constants and values are arranged in order

B) the members can be exhaustive.

 

 

Iii. structure (value type)

1. concept: it is a programmer-defined data type that is similar to a class and has different implementation methods and classes.

2. Comparison with classes

Class	Structure
Reference Type	Value Type
Initial value that can be assigned	Initial values cannot be assigned to declared fields.
The parameter-free constructor can be declared.	No parameter-free constructor can be declared
Must be instantiated	New is not required for instantiation.
Can be inherited except sealed class	Cannot be inherited

3. Declaration Syntax:

Struct name

{

Member

}

Note: The members are fields, attributes, methods, and parameter structures.