в 15:31, 26 мая 2010

2010-05-26T15:31:53Z

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==A simple struct with method==

<source lang="csharp">using System;
struct Fraction {
public int numerator;
public int denominator;
public void Print( ) {
Console.WriteLine( "{0}/{1}", numerator, denominator );
}
}
public class MainClass {
public static void Main( ) {
Fraction f;
f.numerator = 5;
f.denominator = 10;
f.Print( );
Fraction f2 = f;
f.Print( );
f2.numerator = 1;
f.Print( );
f2.Print( );
}
}</source>
<pre class=codeResult>5/10
5/10
5/10
1/10</pre>

==class vs struct==

<source lang="csharp">using System;
using System.Collections.Generic;
using System.Text;

class MyClass {
public int val;
}
struct myStruct {
public int val;
}
class Program {
static void Main(string[] args) {
MyClass objectA = new MyClass();
MyClass objectB = objectA;
objectA.val = 10;
objectB.val = 20;
myStruct structA = new myStruct();
myStruct structB = structA;
structA.val = 30;
structB.val = 40;
Console.WriteLine("objectA.val = {0}", objectA.val);
Console.WriteLine("objectB.val = {0}", objectB.val);
Console.WriteLine("structA.val = {0}", structA.val);
Console.WriteLine("structB.val = {0}", structB.val);
}
}</source>

==Declare a simple struct==

<source lang="csharp">struct Fraction {
public int numerator;
public int denominator;
}
public class MainClass {
public static void Main( ) {
Fraction f;
f.numerator = 5;
f.denominator = 10;
}
}</source>

==Difference between class and struct during the reference passing==

<source lang="csharp">using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class MyClass
{
public int val;
}
struct myStruct
{
public int val;
}
class Program
{
static void Main(string[] args)
{
MyClass objectA = new MyClass();
MyClass objectB = objectA;
objectA.val = 10;
objectB.val = 20;
myStruct structA = new myStruct();
myStruct structB = structA;
structA.val = 30;
structB.val = 40;
Console.WriteLine("objectA.val = {0}", objectA.val);
Console.WriteLine("objectB.val = {0}", objectB.val);
Console.WriteLine("structA.val = {0}", structA.val);
Console.WriteLine("structB.val = {0}", structB.val);
}
}</source>

==Reference value type in a struct==

<source lang="csharp">using System;
struct Point
{
public int X;
public int Y;
}
class MainClass
{
static void Main()
{
Point p1, p2, p3;
p1.X = 10; p1.Y = 10;
p2.X = 20; p2.Y = 20;
p3.X = p1.X + p2.X;
p3.Y = p1.Y + p2.Y;
Console.WriteLine("p1: {0}, {1}", p1.X, p1.Y);
Console.WriteLine("p2: {0}, {1}", p2.X, p2.Y);
Console.WriteLine("p3: {0}, {1}", p3.X, p3.Y);
}
}</source>
<pre class=codeResult>p1: 10, 10
p2: 20, 20
p3: 30, 30</pre>

==Structures==

<p>A struct is similar to a class, but is a value type, not a reference type.</p>
<p>Here is the general form of a struct:</p>

<source lang="csharp">struct name : interfaces {
// member declarations
}</source>
<OL><LI>Structures cannot inherit other structures or classes</LI><LI>Structures cannot be used as a base for other structures or classes.</LI><LI>A structure can implement one or more interfaces.</LI><LI>Structure members can be methods, fields, indexers, properties, operator methods, and events.</LI><LI>Structures can also define constructors, but not destructors.</LI><LI>You cannot define a default (parameterless) constructor for a structure.</LI><LI>A default constructor is automatically defined for all structures, and this default constructor can"t be changed.</LI><LI>Structure members cannot be specified as abstract, virtual, or protected.</LI><LI>When new is used, the specified constructor is called.</LI><LI>When new is not used, the object is still created, but it is not initialized.</LI><LI>When you assign one structure to another, a copy of the structure object is made.</LI></OL>

==struct with value types==

<source lang="csharp">using System;
struct PointerStruct
{
public int x, y;
}
class MainClass
{
public static void Main(string[] args)
{
PointerStruct f1 = new PointerStruct();
f1.x = 100;
f1.y = 100;
PointerStruct f2 = f1;
Console.WriteLine("F1.x = {0}", f1.x);
Console.WriteLine("F1.y = {0}", f1.y);
Console.WriteLine("F2.x = {0}", f2.x);
Console.WriteLine("F2.y = {0}", f2.y);
Console.WriteLine("-> Changing f2.x");
f2.x = 900;
Console.WriteLine("F2.x = {0}", f2.x);
Console.WriteLine("F1.x = {0}\n", f1.x);
}
}</source>
<pre class=codeResult>F1.x = 100
F1.y = 100
F2.x = 100
F2.y = 100
-> Changing f2.x
F2.x = 900
F1.x = 100</pre>

==struct with value types and ref types==

<source lang="csharp">using System;
class MyClass
{
public string x;
public MyClass(string s) {
x = s;
}
}
struct MyStruct
{
public MyClass refType; // Ref type.
public int valueType; // Val type
public MyStruct(string s)
{
refType = new MyClass(s);
valueType = 9;
}
}
class MainClass
{
public static void Main(string[] args)
{
MyStruct valWithRef = new MyStruct("Initial value");
valWithRef.valueType = 6;
MyStruct valWithRef2;
valWithRef2 = valWithRef;
valWithRef2.refType.x = "I am NEW!";
valWithRef2.valueType = 7;
Console.WriteLine("Values after change:");
Console.WriteLine("valWithRef.refType.x is {0}", valWithRef.refType.x);
Console.WriteLine("valWithRef2.refType.x is {0}", valWithRef2.refType.x);
Console.WriteLine("valWithRef.valueType is {0}", valWithRef.valueType);
Console.WriteLine("valWithRef2.valueType is {0}", valWithRef2.valueType);
}
}</source>
<pre class=codeResult>Values after change:
valWithRef.refType.x is I am NEW!
valWithRef2.refType.x is I am NEW!
valWithRef.valueType is 6
valWithRef2.valueType is 7</pre>

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в 15:31, 26 мая 2010

Admin: 1 версия