Replacing Data in an ArrayList

For Each strArray As Geometry In _Geometry

>I am working in VB.net and have a problem that I can't seem to find any
information on. I have an arraylist that I've filled with positional data
from a {numerical control machine} program. I now need to rescan through
the
array list and add values to two of the fields of my structure. I've
setup a
for-each loop:

For Each strArray As Geometry In _Geometry

I can find the data and I can change the structure fields of strArray. I
use a messagebox to see that the data changed and it has. I've tried to
use
_Geometry.remove(index) and then reinsert the line with _Geometry.insert.
I've tried to use ".Item" that is to be used to retrieve and set data but
so
far nothing has worked. I thought that I could make another arraylist and
just transfer the data with the changes to it, but this may cause memory
problems if the data files are long. I don't see a "replace" property.
Each
time I get a:

An unhandled exception of type 'System.InvalidOperationException' occurred
in mscorlib.dll

Additional information: Collection was modified; enumeration operation may
not execute.

>
"StumpedSteve" <St**********@discussions.microsoft.comwrote in message
news:40**********************************@microsof t.com...

I am working in VB.net and have a problem that I can't seem to find any
information on. I have an arraylist that I've filled with positional data
from a {numerical control machine} program. I now need to rescan through
the
array list and add values to two of the fields of my structure. I've
setup a
for-each loop:

For Each strArray As Geometry In _Geometry

I can find the data and I can change the structure fields of strArray. I
use a messagebox to see that the data changed and it has. I've tried to
use
_Geometry.remove(index) and then reinsert the line with _Geometry.insert.
I've tried to use ".Item" that is to be used to retrieve and set data but
so
far nothing has worked. I thought that I could make another arraylist and
just transfer the data with the changes to it, but this may cause memory
problems if the data files are long. I don't see a "replace" property.
Each
time I get a:

An unhandled exception of type 'System.InvalidOperationException' occurred
in mscorlib.dll

Additional information: Collection was modified; enumeration operation may
not execute.

For Each is read only.