Named and Optional Arguments in C#

Now if you run this program, you will get the same result. Please see the following image.

As I said above, we can provide the names in reverse in the method call if we are using the named arguments, right? Please see the preceding method call.

Please run the program and you can see the following output.

You got the same result, right? I hope you said yes.

One of the important uses of a named argument is when you use this in your program it improves the readability of your code. It simply says what your argument is meant to be, or what it is.

Now you can provide the positional arguments too. That means, a combination of both positional argument and named argument. So shall we try that?

In the preceding example we passed 120 as the length and 56 as a named argument for the parameter width.

I hope you enjoyed using named arguments, there are some limitations too. We will explain the limitation of named arguments now.

Limitation of using a Named Argument

Named argument specification must appear after all fixed arguments have been specified.

If you use a named argument before a fixed argument you will get a compile time error as follows.

Named argument specification must appear after all fixed arguments have been specified

Optional Arguments

Reference, MSDN: The definition of a method, constructor, indexer, or delegate can specify that its parameters are required or that they are optional. Any call must provide arguments for all required parameters, but can omit arguments for optional parameters.

As said in the MSDN, an Optional Argument:

• We can omit the argument in the call if that argument is an Optional Argument.
• Every Optional Argument has its own default value.
• It will take a default value if we do not supply the value.
• A default value of an Optional Argument must be a:
  
  1. Constant expression.
  2. Must be a value type such as enum or struct.
  3. Must be an expression of the form default (valueType)
• It must be set at the end of parameter list

Now consider the preceding is our function definition with optional arguments.

Here we have set the value for width as optional and gave value as 56, right? Now we will try to call this function.

If you note, the IntelliSense itself shows you the optional argument as shown in the following image.

Now if you call the function as shown in the preceding code block. The function will be fired and give you the same output.

Note that we did not get any error when compiling and it will give you an output as follows.

Conclusion

I hope you will like this article. Please share with me your valuable thoughts and comments. Your feedback is always welcomed.

Thanks in advance. Happy coding!