Nullable types as function parameter in C#

Question

I saw this in a piece of code and was wondering if someone could help clarifying this for me.

public string MethodName(string str, int? x = null)
{
     if(x != null)
     {
          ....
     }
}

The second function parameter is where I'm confused:

int? x = null

I know about Nullable types, but I'm confused about the syntax here, I've never seen this before. Why is there a "= null" in the input parameter? The way that I'm reading it is it's setting x to null and it will never hit that first if, because x is always null.

Answer 1

Here in the method signature x is an optional parameter, which means you can omit this argument if you do not want to change the parameter's default value. Consider the following calls to this function.

Call 1 : with two parameters

MethodName("AValue",10); // str = AValue and x=10

Call 2 : by skipping optional parameters

MethodName("AValue"); // str = AValue and x=null

Note :-

To define an optional parameter you should assign a default value to that parameter, so that if it is not specified in the function call the default value will be taken.