в 15:31, 26 мая 2010

2010-05-26T15:31:53Z

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2010-05-26T12:16:05Z

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==Instance Counting==

<source lang="csharp">using System.ruponentModel;
public class MainClass
{
public string Name { get; private set; }
public int Age { get; private set; }
private static int InstanceCounter { get; set; }
private static readonly object counterLock = new object();
public MainClass(string name, int age)
{
Name = name;
Age = age;
lock (counterLock)
{
InstanceCounter++;
}
}
}</source>

==Reference a static member variable without using the class name==

<source lang="csharp">public class Employee
{
public Employee()
{
totalHeadCount = 123;
Employee.totalHeadCount = 456;
}
public static int totalHeadCount;
}
public class MainClass
{
static void Main()
{
Employee bob = new Employee();

System.Console.WriteLine("Static Field Employee.totalHeadCount is {0}",Employee.totalHeadCount );
}
}</source>
<pre class=codeResult>Static Field Employee.totalHeadCount is 456</pre>

==Reference Static Field without Instance==

<source lang="csharp">using System;
class MyClass
{
static public int myStaticValue;
}
class Program
{
static void Main()
{
MyClass.myStaticValue = 5;
Console.WriteLine("myStaticValue = {0}", MyClass.myStaticValue);
}
}</source>
<pre class=codeResult>myStaticValue = 5</pre>

==Static field init==

<source lang="csharp">using System;
public class MyClass
{
private static int InitX()
{
Console.WriteLine( "MyClass.InitX()" );
return 1;
}
private static int InitY()
{
Console.WriteLine( "MyClass.InitY()" );
return 2;
}
private static int InitA()
{
Console.WriteLine( "MyClass.InitA()" );
return 3;
}
private static int InitB()
{
Console.WriteLine( "MyClass.InitB()" );
return 4;
}
private int y = InitY();
private int x = InitX();
private static int a = InitA();
private static int b = InitB();
}
public class MainClass
{
static void Main()
{
MyClass a = new MyClass();
}
}</source>
<pre class=codeResult>MyClass.InitA()
MyClass.InitB()
MyClass.InitY()
MyClass.InitX()</pre>

==Static Fields==

<OL><LI>A static member can be accessed before any objects of its class are created.</LI><LI>You can call a static member without referencing to any object.</LI><LI>You can declare both static methods and static variables.</LI><LI>Variables declared as static are, essentially, global variables.</LI><LI>All instances of the class share the same static variable.</LI><LI>A static variable is initialized when its class is loaded.</LI><LI>A static variable always has a value.</LI><LI>If not initialized, a static variable is initialized to zero for numeric values.</LI><LI>If not initialized, a static variable is initialized to null for object references.</LI><LI>If not initialized, a static variable is initialized to false for variables of type bool.</LI></OL>

<source lang="csharp">using System;
class MyClass
{
public MyClass()
{
instanceCount++;
}
public static int instanceCount = 0;
}
class MainClass
{
public static void Main()
{
MyClass my = new MyClass();
Console.WriteLine(MyClass.instanceCount);
MyClass my2 = new MyClass();
Console.WriteLine(MyClass.instanceCount);
}
}</source>
<pre class=codeResult>1
2</pre>

==Use a static constructor.==

<source lang="csharp">using System;

class Cons {
public static int a;
public int b;

// static constructor
static Cons() {
a = 99;
Console.WriteLine("Inside static constructor.");
}

// instance constructor
public Cons() {
b = 100;
Console.WriteLine("Inside instance constructor.");
}
}

class MainClass {
public static void Main() {
Cons ob = new Cons();

Console.WriteLine("Cons.a: " + Cons.a);
Console.WriteLine("ob.b: " + ob.b);
}
}</source>
<pre class=codeResult>Inside static constructor.
Inside instance constructor.
Cons.a: 99
ob.b: 100</pre>

==Use a static field to count instances.==

<source lang="csharp">using System;

class CountInst {
static int count = 0;

// increment count when object is created
public CountInst() {
count++;
}

// decrement count when object is destroyed
~CountInst() {
count--;
}

public static int getcount() {
return count;
}
}

class MainClass {
public static void Main() {
CountInst ob;

for(int i=0; i < 10; i++) {
ob = new CountInst();
Console.WriteLine("Current count: " +
CountInst.getcount());
}

}
}</source>
<pre class=codeResult>Current count: 1
Current count: 2
Current count: 3
Current count: 4
Current count: 5
Current count: 6
Current count: 7
Current count: 8
Current count: 9
Current count: 10</pre>

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в 15:31, 26 мая 2010

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