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David Gr

[C#] Question about functions

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I was wondering if it is possible to pass a function as a parameter for a different function, I think this is possible in C++ but i have no idea if you can do it in C#. Basically, what i want to do is this:
class A
{
    public void B(function C)
    {
        C();
    }
}
So basically, B would be a function in a certain class and C would be passed into that class for maybe rendering or updating. Also, would it be possible to make it so I can set B as a new function in class A so i can access it from other functions in the class? Thanks in advance, David

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This is how you do the second question.


class A
{
public delegate void Function_Call();
public Function_Call function_call;

public void Function_A()
{
System.Windows.Forms.MessageBox.Show("In Function_A");
}

public void Function_B()
{
System.Windows.Forms.MessageBox.Show("In Function_B");
}

public void SetFunction(char function)
{
switch (function)
{
case 'A':
function_call = Function_A;
break;
default:
function_call = Function_B;
break;
}
}

}

A a = new A();
a.SetFunction('A');
a.function_call();






Just have to have the same parameter definition. Well for the most part. We won't get into generic delegates right now.

On a side note and to prevent confusion. In a class they are really called 'methods' not functions. I used the OP terminology just for clarity of what he was asking.

Have to love delegates.
theTroll

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In .NET 3.5 there are a bunch of predefined delegates that you can use (all defined in System.Core.dll in namespace System):


public delegate void Action();
public delegate void Action<T>(T obj);
public delegate void Action<T1, T2>(T1 arg1, T2 arg2);
public delegate void Action<T1, T2, T3>(T1 arg1, T2 arg2, T3 arg3);
public delegate void Action<T1, T2, T3, T4>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
public delegate TResult Func<TResult>();
public delegate TResult Func<T, TResult>(T arg);
public delegate TResult Func<T1, T2, TResult>(T1 arg1, T2 arg2);
public delegate TResult Func<T1, T2, T3, TResult>(T1 arg1, T2 arg2, T3 arg3);
public delegate TResult Func<T1, T2, T3, T4, TResult>(T1 arg1, T2 arg2, T3 arg3, T4 arg4);

// So for the original question a solution is:
class A
{
public void B(Action c)
{
C();
}
}



Quote:
Original post by TheTroll
Have to love delegates.
theTroll


Agreed. And lambda syntax in C# 3.0 makes it even cooler:


// Extension method for IEnumerable<TSource> available in .NET 3.5:
public static double Average<TSource>(this IEnumerable<TSource> source, Func<TSource, int> selector);

var items = new[] { "hello", "gamedev", "chicken", "dog" };
double averageLength = items.Average(x => x.Length);

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