How to handle nullable string as a function parameter

Question

I have function with parameters as given below.

public void myfunction(int a, string b){}

Can we call this function by passing only first parameter and second parameter is optional(nullable string)?

myfunction(5);

If yes then how.

@bigyanshr - string? does not compile. string is already nullable and cannot be used as a type in Nullable<T>. — Chris Dunaway
– Chris Dunaway, Commented Dec 21, 2016 at 20:25

sujith karivelil · Accepted Answer · 2022-08-29 08:21:46Z

16

Actually, your question is a little bit confusing because by the term nullable in the title, meantime you are looking for a method having default parameters/Optional parameters. which can be written like the following:

public void myfunction(int a, string b = ""){}

So that you can call like this myfunction(5); or like myfunction(5,null); or even this: myfunction(5,"Something");

edited Aug 29, 2022 at 8:21

answered Dec 21, 2016 at 7:10

sujith karivelil

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2 Comments

Maksim Simkin Over a year ago

It won't even compile :) The message will be: The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'Nullable<T>'

sujith karivelil Over a year ago

@MaksimSimkin : thank you For correcting me, I have updated the answer

Chris · Accepted Answer · 2016-12-21 12:36:06Z

4

just overload the function as follows:

public void myfunction(int a, string b)
{
   //do stuff
}

public void myfunction(int a)
{
  myfunction(a,string.empty);
}

then call

myFuntion(5);

Note: It's best practice to use string.empty instead of null so have shown that in my example.

edited Dec 21, 2016 at 12:36

answered Dec 21, 2016 at 7:14

Chris

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2 Comments

Max Over a year ago

Why would someone use this, and not the accepted answer? I see no use for this ugly solution.

Chris Over a year ago

One reason would be if you were supporting a legacy .net application as the accepted answer's syntax was not available until c# 4.

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