C ＃ introductory series (XIII) -- getting to know the structure for the first time

Concept

stay  C#  in , A structure is a value type data structure . It enables a single variable to store related data of various data types .struct  Keyword is used to create a structure .

For the representation of these complex data ,C# The structure type is provided to ensure that the data description is consistent with the actual application as much as possible .

C# The type of structure （ Or structure ） It is a kind of user-defined type , It provides users with different data types in practical applications , But interconnected data as a whole provides type support .

C# Different types of data can be combined to form a new structure .

Definition

The definition is in the form of ：

[public] struct  Structure type name ｛
  Member statement ;
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• The member declaration describes the data member of this type （ Or data elements ） And a collection of other types of members .

• The number of members can be as many as you want , Determined by specific needs .

• Curly braces are the bounds of the member list .

When defining a structure type , The type declaration of each data member must be given .

As shown below ：

public  Member type   List of member names ;


public Is an access modifier , Indicates that the data member is allowed to be accessed outside the structure type definition .

If when defining a structure , A data member has not been previously public Access modifier , The structure type variable cannot access this data member .

If multiple members declared are of the same type , Then a member list is formed , The names of members are separated by commas .

• for example , For the representation of coordinate point information, the following structure types can be established .

struct Ponit{
 public int X; // Abscissa
 public int Y; // Ordinate
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The structure belongs to the data type of value type , It can be defined inside a class or outside all classes according to its scope of use .

Generally speaking , Structure types defined inside a class are used only in that class , Structures defined outside the class can be used within the current namespace .

C# in , Structure definitions cannot be placed inside methods or functions .

Additional explanation

The following is a supplementary description of the structure type definition .

• struct Is a keyword that defines the structure type , Does not represent a data type .

• Only use struct Keyword defines the specific structure type before defining the corresponding variable , So it can't be used struct Keyword as the data type of the variable .

• Members of structure types can be either simple data types , It can also be of structure type , That is, the definition of structure can be nested . such as ：

struct Ponit{
 public int X; // Abscissa
 public int Y; // Ordinate
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struct Ponit_3{
 public Ponit Pos_X_Y; 
 public int Z;
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• C# The member type inside the structure is not allowed to be this structure . Such as ：

struct Ponit{
 public int X; // Abscissa
 public int Y; // Ordinate
 //  This is a mistake    Of
 public Ponit pos; 
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• C# In addition to data members , It can also have function members .

• The biggest difference between structs and classes is that classes are reference types , And the structure is the value type . The structure is sealed 、 Not inheritable .