Question

I would like to have something like tkis “int?” but for string. You know if I will not give data to parameter I will not got error. I need some idea to this problem.

Example(4);

public void Example(int, string?){} 

For all of you I give points. Thanks for help. Topic [closed] 🙂

Answer 1

This isn’t available as string is already a reference type, so is already nullable. The ? suffix is syntactic sugar for Nullable<T>, so int? is equivalent to Nullable<int>… and Nullable<T> has a constraint of where T : struct, i.e. T has to be a non-nullable value type… which excludes string.

In other words, you can just write

public void Example(int x, string y)
{
    if (y == null)
    {
        ...
    }
}

Note that this is different from making it an optional parameter. Passing in a null value is still passing in a value. If you want to make it an optional parameter you can do that too:

public void Example(int x, string y = "Fred")

...

Example(10); // Equivalent to Example(10, "Fred");