Determine Number and Count of Unique Extensions

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What I am trying to do is come up with a way to determine how many unique
extensions there are within a directory and its sub directories. Within the
loop that recurses root folder, I am attempting to use a SortedList. Below
is the code:

private System.Collections.SortedList _ArrayListOfExtensions = new
SortedList(new CaseInsensitiveComparer());

System.Int32 myIndexOfValue = -1;
myIndexOfValue =
this._ArrayListOfExtensions.IndexOfKey(myCurrentFi le.Extension.ToLower());

if (myIndexOfValue == -1)
{
this._ArrayListOfExtensions.Add(myCurrentFile.Exte nsion.ToLower(), 1);
}

The Exception error that I am getting is:
"Unable to cast object of type 'System.Collections.DictionaryEntry' to type
'System.String'."

Any help would be appreciated as to how to correct this error. Also, if you
know of a better way (I have tried several) to accomplish the above, I am
open to your suggestions.

The results should be similar to:

15 .docx
17 .doc
14 .txt
7 .exe
etc...

Thanks!
Edwin

[Jon Skeet [C# MVP]]

Edwin <Ed***@discussions.microsoft.comwrote:

What I am trying to do is come up with a way to determine how many unique
extensions there are within a directory and its sub directories. Within the
loop that recurses root folder, I am attempting to use a SortedList. Below
is the code:

private System.Collections.SortedList _ArrayListOfExtensions = new
SortedList(new CaseInsensitiveComparer());

SortedList isn't an ArrayList - it's a dictionary, basically.

Are you using .NET 3.5? LINQ would make this pretty much trivial...

--
Jon Skeet - <sk***@pobox.com>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com

[Edwin]

Thank you Jon for your reply,

I am using Visual Studio 2008 Professional with .Net 3.5

I appreciate your assistance.

Edwin

"Jon Skeet [C# MVP]" <sk***@pobox.comwrote in message
news:MP*********************@msnews.microsoft.com. ..

Edwin <Ed***@discussions.microsoft.comwrote:

>What I am trying to do is come up with a way to determine how many unique
extensions there are within a directory and its sub directories. Within
the
loop that recurses root folder, I am attempting to use a SortedList.
Below
is the code:

private System.Collections.SortedList _ArrayListOfExtensions = new
SortedList(new CaseInsensitiveComparer());

SortedList isn't an ArrayList - it's a dictionary, basically.

Are you using .NET 3.5? LINQ would make this pretty much trivial...

--
Jon Skeet - <sk***@pobox.com>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com

[Jon Skeet [C# MVP]]

Edwin <ed*********@msn.comwrote:

Thank you Jon for your reply,

I am using Visual Studio 2008 Professional with .Net 3.5

I appreciate your assistance.

In which case I suggest you look at the overloads of Enumerable.GroupBy
which take an IEqualityComparer<TKey>.

--
Jon Skeet - <sk***@pobox.com>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com