Optioan Arguments in C#

[fid]

How do i write a function that will accept optional arguments?

ie: so the function can be called
_obj.DoSomething(arg1, arg2, arg3);
or
_obj.DoSomething(arg1);
or simply as
_obj.DoSomething();

how do i set up
public string DoSomething(int arg1, int arg2, int arg3)
etc... without getting the "invalid number of arguments" error ??

thanks in advance

fid

 

[Larsson]

Hi!

It’s simple when you know how to do it. So I will try to explain how it's done.
The thing you are talking about is called function overloading. It gives the possibility to have different versions of the same function.
You have to have different function signatures so that the compiler can understand which function overload to use. A function signature is the parameter list, for example (int a, int b). This signature is different with this: (int a, string b), they have the same number of arguments, but they are different types.
Here is a short example:

public class SomeClass
{

public int SomeFunction(int a)
{
return a*a;
}

public int SomeFunction(int a, int b)
{
return a*b;
}

public int SomeFunction(int a, int b, int c)
{
return a*b*c;
}

//This overload doesn't work, the signature is
//the same as in the first function.
public void SomeFunction(int a)
{
Console.WriteLine (a);
}

public void SomeFunction (int a, string b)
{
Console.WriteLine("a is {0} and b is {1}",
a, b);
}
}

I hope that this clear things up. The chapter 7.4 in the C# Language specification has more info.

Markus Larsson