в 15:31, 26 мая 2010

2010-05-26T15:31:53Z

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2010-05-26T12:16:11Z

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==Add Length property to MyArray==

<source lang="csharp">using System;

class MyArray {
int[] a;
int len;

public bool errflag;

public MyArray(int size) {
a = new int[size];
len = size;
}

public int Length {
get {
return len;
}
}

public int this[int index] {
get {
if(indexCheck(index)) {
errflag = false;
return a[index];
} else {
errflag = true;
return 0;
}
}

set {
if(indexCheck(index)) {
a[index] = value;
errflag = false;
}
else errflag = true;
}
}

private bool indexCheck(int index) {
if(index >= 0 & index < Length)
return true;
return false;
}
}

class MainClass {
public static void Main() {
MyArray myArray = new MyArray(5);
int x;

for(int i=0; i < myArray.Length; i++)
myArray[i] = i*10;

for(int i=0; i < myArray.Length; i++) {
x = myArray[i];
if(x != -1) Console.Write(x + " ");
}
Console.WriteLine();
}
}</source>
<pre class=codeResult>0 10 20 30 40</pre>

==Add statement to the getter and setter of a property==

<source lang="csharp">public class A
{
private int myValue;
public int MyValue
{
get
{
System.Console.WriteLine( "Getting myValue" );
return myValue;
}
set
{
System.Console.WriteLine( "Setting myValue" );
myValue = value;
}
}
}
public class MainClass
{
static void Main()
{
A obj = new A();
obj.MyValue = 1;
System.Console.WriteLine( "obj.Value = {0}",
obj.MyValue );
}
}</source>
<pre class=codeResult>Setting myValue
Getting myValue
obj.Value = 1</pre>

==A simple property example==

<source lang="csharp">using System;

class SimpProp {
int prop;

public SimpProp() {
prop = 0;
}

public int MyProp {
get {
return prop;
}
set {
prop = value;
}
}
}

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

Console.WriteLine("Original value of ob.MyProp: " + ob.MyProp);

ob.MyProp = 100;
Console.WriteLine("Value of ob.MyProp: " + ob.MyProp);

Console.WriteLine("Attempting to assign -10 to ob.MyProp");
ob.MyProp = -10;
Console.WriteLine("Value of ob.MyProp: " + ob.MyProp);
}
}</source>
<pre class=codeResult>Original value of ob.MyProp: 0
Value of ob.MyProp: 100
Attempting to assign -10 to ob.MyProp
Value of ob.MyProp: -10</pre>

==Combine readonly and read only property==

<source lang="csharp">using System;
public sealed class Value
{
public int intValue = 10;
}
public sealed class MyController
{
public MyController( Value pimpl ) {
this.pimpl = pimpl;
}
public int IntValue {
get {
return pimpl.intValue;
}
}
private readonly Value pimpl;
}
public sealed class MainClass
{
static void Main() {
Value someNumber = new Value( );
}
}</source>

==Define accessors for Properties with get and set==

<source lang="csharp">class MyClass
{
private string name;

public string Name
{
get
{
return name;
}
set
{
name = value;
}
}
}</source>

==Do calculation with Property==

<source lang="csharp">using System;
public class SomeClass
{
private int num;
public SomeClass(int i)
{
num = i;
}
public int Num
{
get { return num; }
set { num = value; }
}
}

public class CompoundAssPropApp
{
public static void Main(string[] args)
{
SomeClass sc = new SomeClass(42);
Console.WriteLine("{0}", sc.Num);

sc.Num = sc.Num + 5;
Console.WriteLine("{0}", sc.Num);
}
}</source>

==Invoke Indexed Property Demo==

<source lang="csharp">using System;
using System.Reflection;
using System.Globalization;
class Class1
{

DateTime[] dateTimes = new DateTime[10];
public DateTime this[int index]
{
get{ return dateTimes[index]; }
set{ dateTimes[index] = value;}
}

private DateTime dateOfBirth;
public DateTime DateOfBirth
{
get{ return dateOfBirth; }
set{ dateOfBirth = value; }
}

public void Test()
{
Console.WriteLine("Test method called");
}

private string field;

public string Property
{
get{ return field; }
set{ field = value; }
}

}

class MainClass{

static void Main(string[] args)
{
Type type = typeof(Class1);
Console.WriteLine(type.FullName);

object o = Activator.CreateInstance(type);
type.InvokeMember( "Item",
BindingFlags.Instance |
BindingFlags.SetProperty | BindingFlags.Public,
null, o, new object[]{0, new DateTime(1966, 2, 12)});

Console.WriteLine(((Class1)o)[0].ToString());
}
}</source>

==Properties and its Restrictions==

<OL><LI>A property consists of a name along with get and set accessors.</LI><LI>The accessors are used to get and set the value of a variable.</LI></OL>
<p>The general form of a property is shown here:</p>

<source lang="csharp">type propertyName {
get {
// get accessor code
}

set {
// set accessor code
}
}</source>
<OL><LI>A property cannot be passed as a ref or out parameter to a method.</LI><LI>You cannot overload a property.</LI><LI>A property should not alter the state of the underlying variable when the get accessor is called.</LI></OL>
<p>(Quote from C# The Complete Reference, Publisher: Osborne/McGraw-Hill, March 8, 2002,
Language: English ISBN-10: 0072134852 ISBN-13: 978-0072134858)</p>

==Property And its associated Field==

<source lang="csharp">using System;

class MyClass
{
private int privateInnerValue = 10;
public int MyValue
{
set {
privateInnerValue = value;
}
get {
return privateInnerValue;
}
}
}
class MainClass
{
static void Main()
{
MyClass c = new MyClass();
Console.WriteLine("MyValue: {0}", c.MyValue);
c.MyValue = 20;
Console.WriteLine("MyValue: {0}", c.MyValue);
}
}</source>
<pre class=codeResult>MyValue: 10
MyValue: 20</pre>

==Property Getter and Setter==

<source lang="csharp">using System;

class Address
{
protected string city;
public string City
{
get { return city; }
}

protected string zipCode;
public string ZipCode
{
get { return zipCode; }
set
{
zipCode = value;
city = "Atlanta";
}
}
}

class PropertyApp
{
public static void Main()
{
Address addr = new Address();
addr.ZipCode = "30338";
string zip = addr.ZipCode;

Console.WriteLine("The city for ZIP code {0} is {1}", addr.ZipCode, addr.City);
}
}</source>

==Put logic to property setter==

<source lang="csharp">using System;
using System.Collections.Generic;
using System.Text;
class MainClass
{
static void Main(string[] args)
{
Person person = new Person();
person.SetName("A", "B");
Console.WriteLine("The person"s full name is {0}",person.FullName);
person.FullName = "A b c";
Console.WriteLine("The person"s full name is {0}",person.FullName);
}
}
class Person
{
private string _lastname;
private string _firstname;
public void SetName(string lastname, string firstname)
{
_lastname = lastname;
_firstname = firstname;
}
public string FullName
{
get
{
return _firstname + " " + _lastname;
}
set
{
string[] names = value.Split(new string[] { " " },StringSplitOptions.RemoveEmptyEntries);
_firstname = names[0];
_lastname = names[names.Length - 1];
}
}
}</source>
<pre class=codeResult>The person"s full name is B A
The person"s full name is A c</pre>

==Readonly property==

<source lang="csharp">using System;
class MyClass
{
public double A = 3;
public double B = 4;

public double MyValue
{
get { return A * B ; }
}
}
class MainClass
{
static void Main()
{
MyClass c = new MyClass();
Console.WriteLine("MyValue: {0}", c.MyValue);
}
}</source>
<pre class=codeResult>MyValue: 12</pre>

==throw Exception from property setting==

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

public class MyClass
{
public readonly string Name;
private int intVal;
public int Val
{
get
{
return intVal;
}
set
{
if (value >= 0 && value <= 10)
intVal = value;
else
throw (new ArgumentOutOfRangeException("Val", value,"Val must be assigned a value between 0 and 10."));
}
}
public override string ToString()
{
return "Name: " + Name + "\nVal: " + Val;
}
private MyClass() : this("Default Name")
{
}
public MyClass(string newName)
{
Name = newName;
intVal = 0;
}
}
class Program
{
static void Main(string[] args)
{
MyClass myObj = new MyClass("My Object");
Console.WriteLine("myObj created.");
for (int i = -1; i <= 0; i++)
{
try
{
myObj.Val = i;
}
catch (Exception e)
{
Console.WriteLine("Exception {0} thrown.", e.GetType().FullName);
Console.WriteLine("Message:\n\"{0}\"", e.Message);
}
}
}
}</source>

==Use properties to set and get private members.==

<source lang="csharp">using System;

class Shape {
double pri_width; // now private
double pri_height; // now private

// Properties for width and height.
public double width {
get { return pri_width; }
set { pri_width = value; }
}

public double height {
get { return pri_height; }
set { pri_height = value; }
}

public void showDim() {
Console.WriteLine("Width and height are " +
width + " and " + height);
}
}

class Triangle : Shape {
public string style; // style of triangle

public double area() {
return width * height / 2;
}

public void showStyle() {
Console.WriteLine("Triangle is " + style);
}
}

class MainClass {
public static void Main() {
Triangle t1 = new Triangle();
Triangle t2 = new Triangle();

t1.width = 4.0;
t1.height = 4.0;
t1.style = "isosceles";

t2.width = 8.0;
t2.height = 12.0;
t2.style = "right";

Console.WriteLine("Info for t1: ");
t1.showStyle();
t1.showDim();
Console.WriteLine("Area is " + t1.area());

Console.WriteLine();

Console.WriteLine("Info for t2: ");
t2.showStyle();
t2.showDim();
Console.WriteLine("Area is " + t2.area());
}
}</source>
<pre class=codeResult>Info for t1:
Triangle is isosceles
Width and height are 4 and 4
Area is 8
Info for t2:
Triangle is right
Width and height are 8 and 12
Area is 48</pre>

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Csharp/CSharp Tutorial/Class/Properties - История изменений

в 15:31, 26 мая 2010

Admin: 1 версия