作业帮请举例说明C#中委托的用法?
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/10 21:14:17
请举例说明C#中委托的用法?
using System;
public class SamplesDelegate {
// Declares a delegate for a method that takes in an int and returns a String.
public delegate String myMethodDelegate( int myInt );
// Defines some methods to which the delegate can point.
public class mySampleClass {
// Defines an instance method.
public String myStringMethod ( int myInt ) {
if ( myInt > 0 )
return( "positive" );
if ( myInt < 0 )
return( "negative" );
return ( "zero" );
}
// Defines a static method.
public static String mySignMethod ( int myInt ) {
if ( myInt > 0 )
return( "+" );
if ( myInt < 0 )
return( "-" );
return ( "" );
}
}
public static void Main() {
// Creates one delegate for each method.For the instance method,an
// instance (mySC) must be supplied.For the static method,use the
// class name.
mySampleClass mySC = new mySampleClass();
myMethodDelegate myD1 = new myMethodDelegate( mySC.myStringMethod );
myMethodDelegate myD2 = new myMethodDelegate( mySampleClass.mySignMethod );
// Invokes the delegates.
Console.WriteLine( "{0} is {1}; use the sign \"{2}\".",5,myD1( 5 ),myD2( 5 ) );
Console.WriteLine( "{0} is {1}; use the sign \"{2}\".",-3,myD1( -3 ),myD2( -3 ) );
Console.WriteLine( "{0} is {1}; use the sign \"{2}\".",0,myD1( 0 ),myD2( 0 ) );
}
}
/*
This code produces the following output:
5 is positive; use the sign "+".
-3 is negative; use the sign "-".
0 is zero; use the sign "".
*/