what is delegate in asp.net

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C#

hi,
what is the use of delegate in C#,explain with realtime practical example.

Posted 15-Jun-12 3:09am

nira.parmar

Updated 15-Jun-12 4:20am

bbirajdar

v2

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ZurdoDev 15-Jun-12 9:11am

Have you googled this? This sounds like a homework question.

bbirajdar 15-Jun-12 10:20am

Edit: Added the tag Homework

3 solutions

Solution 3

I am not sure if you may have seen the following. These two are equivalent:

C#

datePicker.Loaded += (s, a) =>
{
    var textBox1 = (TextBox)datePicker.Template.FindName("PART_TextBox", datePicker);
    textBox1.Background = datePicker1.Background;
};

datePicker.Loaded += delegate
{
    var textBox1 = (TextBox)datePicker.Template.FindName("PART_TextBox", datePicker);
    textBox1.Background = datePicker1.Background;
};

Both these use the RoutedEventHandler delegate:

public delegate void RoutedEventHandler(object sender, RoutedEventArgs e);

You could also do the following

C#

void datePicker_Loaded(object sender, RoutedEventArgs e)
{
    var textBox1 = (TextBox)datePicker.Template.FindName("PART_TextBox", datePicker);
    textBox1.Background = datePicker1.Background;
}

then you would assign the handler as:

DatePicker.Loaded += new RoutedEventHandler(datePicker1_Loaded);

or

DatePicker.Loaded += datePicker1_Loaded;

Posted 15-Jun-12 7:54am

Clifford Nelson

Solution 2

Generally Delegates are Similar to C++ Function Pointers.

Posted 15-Jun-12 4:34am

Ranjith Reddy CSE

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OriginalGriff · Accepted Answer · 2012-06-15T03:49:00

A Delegate is a reference to a function, in the same way that a TextBox variable is a reference to teh instance of a TextBox that appears on the screen.

They are surprisingly handy: you can use them to write code that can work to a variety of destinations without changing the code. For example, you could write a Print method that took a delegate:

C#

private void DoPrint()
    {
    string text = "hello world!";
    Print(text, PrintConsole);
    Print(text, PrintTextbox);
    }
private void PrintConsole(string s)
    {
    Console.WriteLine("Console: " + s);
    }
private void PrintTextbox(string s)
    {
    myTextBox.Text = "TextBox: " + s;
    }
private delegate void printDestination(string s);
private void Print(string s, printDestination pd)
    {
    pd("From Print: " + s);
    }

You can completely change what happens to the text without changing the code in the Print method.

There are a lot of other uses, but that's the general idea.