SUNWEN tutorial - C# advanced (7)

What I want to talk about is the structure (struct) in C#. Note that the structure I am talking about here does not refer to the language structure of C#. What I am talking about here is something relative to the class (class). Below I will talk about it with the class. For comparison, let’s talk about this struct.

The following example describes how to create a structure with attributes, methods and a field. And how to use it.

000: // Structsstruct1.cs
001: using System;
002: struct SimpleStruct
003: {
004: PRivate int xval;
005: public int : if (value 012: xval = value;
013: }
014: }
015: public void DisplayX()
016: {
017: Console.WriteLine("The stored value is: {0 }", xval);
018: }
019: }
020:
021: class TestClass
022: {
023: public static void Main()
024: {
025: SimpleStruct ss = new SimpleStruct();
026: ss. It seems that structures and classes are the same. Indeed, if you use classes to rewrite this program, the result will be the same. However, it is obvious that two identical things cannot appear together. Structure (struct) is Value (value) type, while classes are reference types. In this way, you can use structures to create objects like built-in types.

Also, if you use a new keyword to create an instance of a class , it is allocated on the heap, and when new is used to create an instance of a structure, it is allocated on the stack. This will improve our performance a lot (what M$ said). Good Okay, let's look at the following example again:


000: // Structsstruct2.cs
001: using System;
002:
003: class TheClass
004: {

005: public int x;

006: }

007:

008: struct TheStruct
009: {

010: public int x;

011: }

012:

013: class TestClass
014: {
015: public static void structtaker(TheStruct s)
016: {
017: s.x = 5;
018: }
019: public static void classtaker(TheClass c)
020: {
021: c.x = 5;
022: }
023: public static void Main()
024: {
025: TheStruct a = new TheStruct();
026: TheClass b = new TheClass();
027: a.x = 1;
028: b.x = 1;
029: structtaker(a);
030: classtaker(b );
031: Console.WriteLine("a.x = {0}", a.x);
032: Console.WriteLine("b.x = {0}", b.x);
033: }
034: }

This example The output of is a reference. So the output of a.x= is 1, unchanged, but b.x has changed.

Another difference is that the structure can be instantiated without new, but the class does. If you do not use new to instantiate a structure, then all fields will remain unallocated until all fields are initialized. Like classes, structures can implement interfaces. More importantly, structures have no inheritance. A structure cannot inherit from other classes, nor can It is the base class of other classes.

Example 3:

interface IImage
{
void Paint();
}

struct Picture : IImage
{

public void Paint()

{

// painting code goes here

}
private int x, y, z; // other struct members

}

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