Remove method from IList interface not recognized when I try to call it from an Array object

user_3783002 0
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According to the official docs, arrays in C# implement the following interfaces:

  • IList
  • IEnumerable

In the docs for IList, I see that one of the listed methods is a Remove method which does the following:

Removes the first occurrence of a specific object from the IList.

I wanted to use this method, so I wrote the following minimal program:

class RemoveAllOccurences {

    static void Main() 
    {
        int[] a = {1, 0, 0, 3};
        
        a.Remove(0);

    }
}

I then compiled with the following:

csc test.cs -out:test.exe

Running the executable threw the following error:

remove_issue.cs(7,11): error CS1061: 'int[]' does not contain a definition for 'Remove' and no accessible extension method 'Remove' accepting a first argument of type 'int[]' could be found (are you missing a using directive or an assembly reference?)

I'm not sure why Remove is not recognized, since as I mentioned before it is part of the IList interface shown in the docs.

What am I doing wrong here?

interface arrays c#
1 Answers

Arrays implement IList.Remove via explicit interface implementation, which means you can only access it via a reference with a compile-time type of the interface type. So for example:

int[] a = {1, 0, 0, 3};
IList list = a;
list.Remove(0);

That compiles with no problem. However, it will then throw an exception (NotSupportedException) at execution time because arrays are of fixed size - Remove and Add operations don't make sense on them. That's why those methods are implemented with explicit interface implementation, to avoid you using them inappropriately...

user_226560
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