How can we declare Optional Parameters in C#.net? [duplicate]

问题

I am using a method for doing some action, i want the method to be written only once by using Optional Parameters in C#, other than Method Overloading is there any?

回答1:

New to visual studio 2010

named and optional arguments

for example

public void ExampleMethod(int required, string optionalstr = "default string",
int optionalint = 10)
{
}

回答2:

Have a look at following code

Library to use

using System.Runtime.InteropServices;

Function declaration

private void SampleFunction([Optional]string optionalVar, string strVar)
{
}

And while giving call to function you can do like this

SampleFunction(optionalVar: "someValue","otherValue");

SampleFunction("otherValue");

Reply if it helps.!:)

回答3:

Yes, use optional parameters (introduced in C# 4).

public void ExampleMethod(int required, string optionalstr = "default string",
    int optionalint = 10)

When you provide a default value to a formal parameter, it becomes optional.

For prior versions, overloads are the only option.

回答4:

They have been introduced in C# 2010 (that is generally VS2010 with Framework 4.0). See Named and Optional Arguments (C# Programming Guide).

In previous C# versions you're stuck with overloads (or param arrays).

回答5:

If you use C# 4.0 it is.

You can then define your method like this:

public void Foo( int a = 3, int b = 5 ){
  //at this point, if the method was called without parameters, a will be 3 and b will be 5.
}

来源：https://stackoverflow.com/questions/5116625/how-can-we-declare-optional-parameters-in-c-net

标签

optional