Why can I apply an indexer to an ICollection in VB.Net, but not in C#

Question

Was converting some code from VB.Net to C#, when I came across this, in some code using the Ionic Zip library:

Dim zipEntry1 As ZipEntry = zipFile1.Entries(0         


        

Answer 1

zipFile1.Entries(0) invokes the so-called Default Query Indexer, which is a little-known feature defined in the VB language specification:

Default Query Indexer

Every queryable collection type whose element type is T and does not already have a default property is considered to have a default property of the following general form:

Public ReadOnly Default Property Item(index As Integer) As T
    Get
        Return Me.ElementAtOrDefault(index)
    End Get
End Property