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How to use TypeOf()?

I have a collection that holds DataGridTextBox Column types, which I
then bind to a DataGrid. I loop through all of the
DataGridTextBox Column that were created and add them to the collection
like this

for(int i=0; i<dataGridStyle ColumnCollectio n.Count; i++)
{

gridTableStyle. GridColumnStyle s.Add((DataGrid TextBoxColumn)d ataGridStyleCol umnCollection[i]);
}

Sometimes, I'll have a DataGridBoolCol umn, which breaks the above code.
I'm trying to put in a conditional that checks the type. This always
gives a warning:

The given expression is never of the provided
('System.Window s.Forms.DataGri dBoolColumn') type

[the expression]
if(dataGridStyl eColumnCollecti on[i].GetType() is DataGridTextBox Column)

gridTableStyle. GridColumnStyle s.Add((DataGrid TextBoxColumn)d ataGridStyleCol umnCollection[i]);

[In the debugger while looping]
- dataGridStyleCo lumnCollection[i].GetType() {System.Runtime Type} System.RuntimeT ype

+ System.Type {"System.Window s.Forms.DataGri dBoolColumn"} System.Type

The debugger shows it is of the provided type. Neither of the above
conditionals ever run. They always evaluate to false. What does the
compiler and debugger say two different things?

Should I use something else to determine the column type?

Thanks,
Brett

Jan 12 '06 #1
1 3283
Brett Romero <ac*****@cygen. com> wrote:
I have a collection that holds DataGridTextBox Column types, which I
then bind to a DataGrid. I loop through all of the
DataGridTextBox Column that were created and add them to the collection
like this
<snip>
[the expression]
if(dataGridStyl eColumnCollecti on[i].GetType() is DataGridTextBox Column)
<snip>
The debugger shows it is of the provided type. Neither of the above
conditionals ever run. They always evaluate to false. What does the
compiler and debugger say two different things?


Because what you're asking is whether the type System.Type is an
instance of DataGridTextCol umnBox, which it never is. You're sort of in
a half-way house between:

if(dataGridStyl eColumnCollecti on[i].GetType() ==
typeof(DataGrid TextBoxColumn))

and

if(dataGridStyl eColumnCollecti on[i] is DataGridTextBox Column)

Either of those would work (although the first one won't "match" if you
give it an instance of something derived from DataGridTextBox Column.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
Jan 12 '06 #2

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