How do I check the type of the value represented in a system.type?

[Don]

I have an array of System.type and I need to go through the array and
perform different logic depending on the type stored in the array.

I want to do:
if (typeof typeCollection( i) is String) then
'some logic
elseif (typeof typeCollection( i) is int32) then
'some logic
.....

The problem is the type of my object is always system.type. If I
toString it I get the text that represents the data type but I don't
really like string comparisions when I'm trying to determine type.

I am storing the type of data from a dataColumn in this array as
follows:
typeCollection. add(dataColumn. dataType())

I then add the array to the viewState so I can access the data after a
postback.

Thanks,
Don

[S. Justin Gengo]

Don,

I think you need to store your items as an array of System.Object instead of
System.Type. Then when you check them you won't always get back System.Type.

--
Sincerely,

S. Justin Gengo, MCP
Web Developer / Programmer

www.aboutfortunate.com

"Out of chaos comes order."
Nietzsche
"Don" <ch*********@ho tmail.com> wrote in message
news:11******** *************@g 43g2000cwa.goog legroups.com...

I have an array of System.type and I need to go through the array and
perform different logic depending on the type stored in the array.

I want to do:
if (typeof typeCollection( i) is String) then
'some logic
elseif (typeof typeCollection( i) is int32) then
'some logic
....

The problem is the type of my object is always system.type. If I
toString it I get the text that represents the data type but I don't
really like string comparisions when I'm trying to determine type.

I am storing the type of data from a dataColumn in this array as
follows:
typeCollection. add(dataColumn. dataType())

I then add the array to the viewState so I can access the data after a
postback.

Thanks,
Don

[Don]

I have a DataTable filled with data from the database which I bind to
the datagrid. On post back I need to be able to determine the data
type for each cell on the selected row.

To do this I iterate through the columns in the data table and add the
type of each column to the array as shown below:
dim col as datacolumn

for each col in datatable.colum n
typeCollection. add(col.DataTyp e())
next

I can't add the column to the array because it is not serializable and
I need to store it in the ViewState. I don't have an actual object to
add to the array. I could iterate through the first row and add that
object to the array but I still need the DataTypes when I have no rows
returned.

[S. Justin Gengo]

Don,

Ahhhh, didn't know that. I think you could do this:

Going with what you said earlier about ToString working go ahead and store
each column type using ToString

typeCollection. add(col.DataTyp e().ToString)

But then when you do your comparison use the System.Type object's GetType
method.

If (System.Type.Ge tType(typeColle ction(i).toStri ng) Is String) Then

The System.Type.Get Type function returns a type based on the string name.

--
Sincerely,

S. Justin Gengo, MCP
Web Developer / Programmer

www.aboutfortunate.com

"Out of chaos comes order."
Nietzsche
"Don" <ch*********@ho tmail.com> wrote in message
news:11******** **************@ g47g2000cwa.goo glegroups.com.. .

I have a DataTable filled with data from the database which I bind to
the datagrid. On post back I need to be able to determine the data
type for each cell on the selected row.

To do this I iterate through the columns in the data table and add the
type of each column to the array as shown below:
dim col as datacolumn

for each col in datatable.colum n
typeCollection. add(col.DataTyp e())
next

I can't add the column to the array because it is not serializable and
I need to store it in the ViewState. I don't have an actual object to
add to the array. I could iterate through the first row and add that
object to the array but I still need the DataTypes when I have no rows
returned.

[Don]

This does not work. As you stated GetType returns a type based on the
string name and I already have that in the typeCollection in array.
The problem is that the type of this obejct is System.Type not
System.String so I can't do the typeOf operation.

[S. Justin Gengo]

Don,

Did you try it?

Works fine for me.

Here's the code I used, run it and see.

Dim DataTable1 As New DataTable

DataTable1.Colu mns.Add(New DataColumn("Col umn1", GetType(String) ))

DataTable1.Colu mns.Add(New DataColumn("Col umn2", GetType(Int32)) )

DataTable1.Colu mns.Add(New DataColumn("Col umn3", GetType(Object) ))

DataTable1.Colu mns.Add(New DataColumn("Col umn4", GetType(DateTim e)))

Dim ArrayList As New ArrayList

For Each Column As DataColumn In DataTable1.Colu mns

ArrayList.Add(C olumn.DataType. ToString)

Next

Dim ColumnCount, ColumnLoop As Int32

ColumnCount = ArrayList.Count - 1

Dim TypeString As String

For ColumnLoop = 0 To ColumnCount

If System.Type.Get Type(ArrayList( ColumnLoop).ToS tring) Is GetType(Int32)
Then

Response.Write( "Int32 Found in Column " & ColumnLoop.ToSt ring)

End If

Next
--
Sincerely,

S. Justin Gengo, MCP
Web Developer / Programmer

www.aboutfortunate.com

"Out of chaos comes order."
Nietzsche
"Don" <ch*********@ho tmail.com> wrote in message
news:11******** **************@ g47g2000cwa.goo glegroups.com.. .

This does not work. As you stated GetType returns a type based on the
string name and I already have that in the typeCollection in array.
The problem is that the type of this obejct is System.Type not
System.String so I can't do the typeOf operation.