Delegate

Nitin Bhardwaj

14y2.4k.NET

Hi,
can we create delegate of constructor?
Please give me a example.

5 Replies

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Vulpes14y ago
Accepted answer
If you're asking whether a constructor (as opposed to an ordinary method) can be assigned to a delegate, or added to its invocation list, then the answer is that it can't - not directly anyway.

You can do it indirectly by wrapping a constructor call in a lambda expression like this:

Func func = chars => new string(chars);
string str = func(new char[]{'a', 'b', 'c'});
Console.WriteLine(str); // abc

but there doesn't seem much point.

What are you trying to do exactly?
Vulpes14y ago
Sure, here's a simple example of using a delegate.

First we define a delegate type, MyDelegate, which takes an int parameter but doesn't have a return value. This means that the delegate is compatible with both the Treble and Square methods.

We then create a variable 'del' of the delegate type to which we can assign compatible methods.

Initially, we just call the Treble method with an argument of 10 by invoking the delegate.

However, we then add the Square method to the delegate (making it 'multicast') and invoke both methods with an argument of 20:

using System;

delegate void MyDelegate(int number);

class Test
{
static void Main()
{
MyDelegate del = Treble;
del(10); // invoke with an argument of 10

// add another method to 'del's invocation list
del += Square;
del(20); // invoke with an argument of 20
Console.ReadKey();
}

static void Treble(int number)
{
Console.WriteLine("{0} x 3 = {1}", number, number * 3);
}

static void Square(int number)
{
Console.WriteLine("{0} x {0} = {1}", number, number * number);
}
}

The output should be:

10 x 3 = 30
20 x 3 = 60
20 x 20 = 400
Nitin Bhardwaj14y ago
Give me an example.
Vulpes14y ago
Please check my answer to this previous thread:

http://www.c-sharpcorner.com/Forums/Thread/180985/delegate-in-C-Sharp.aspx
Nitin Bhardwaj14y ago
Brief describe the delegate?