Everything I find about IDictionaryEnumerator says that they are readonly.
I'm somewhat confused by the following example. The MsgBox 4 lines from the
bottom will never be run. In the first While loop the Clear is called, but
the value is never added back into the ht object. So why is the hashtable
cleared when I get the to While m block? Shouldn't this not happen since the
Enumerator is readonly?
Thanks in advance for any explanation.
---
Dim ht As New Hashtable()
Dim I As Integer
For I = 1 To 5
Dim h As New Hashtable()
h.Add(I, I)
ht.Add(I, h)
Next I
Dim en As IDictionaryEnumerator = ht.GetEnumerator()
While en.MoveNext
en.Value.clear()
End While
Dim ne As IDictionaryEnumerator = ht.GetEnumerator()
While ne.MoveNext
Dim m As IDictionaryEnumerator = ne.Value.GetEnumerator()
While m.MoveNext
MsgBox(m.Key & "," & m.Value)
End While
End While
End Sub 3 2673
All these references refer to the same collections of objects so when you
cleared them in the While loop, you leave nothing to enumerate through
OHM
Chris Skaryd wrote: Everything I find about IDictionaryEnumerator says that they are readonly.
I'm somewhat confused by the following example. The MsgBox 4 lines from the bottom will never be run. In the first While loop the Clear is called, but the value is never added back into the ht object. So why is the hashtable cleared when I get the to While m block? Shouldn't this not happen since the Enumerator is readonly?
Thanks in advance for any explanation.
--- Dim ht As New Hashtable()
Dim I As Integer
For I = 1 To 5
Dim h As New Hashtable()
h.Add(I, I) ht.Add(I, h)
Next I
Dim en As IDictionaryEnumerator = ht.GetEnumerator()
While en.MoveNext en.Value.clear() End While
Dim ne As IDictionaryEnumerator = ht.GetEnumerator()
While ne.MoveNext Dim m As IDictionaryEnumerator = ne.Value.GetEnumerator()
While m.MoveNext MsgBox(m.Key & "," & m.Value) End While End While
End Sub
Regards - OHM# On**********@BTInternet.com
I sort of figured that was what was happening, but I thought that the
IDictionaryEnumerator was readonly. Shouldn't the Clear method have thrown
an error?
One Handed Man [ OHM# ] wrote: All these references refer to the same collections of objects so when you cleared them in the While loop, you leave nothing to enumerate through
OHM
Chris Skaryd wrote:
Everything I find about IDictionaryEnumerator says that they are readonly.
I'm somewhat confused by the following example. The MsgBox 4 lines from the bottom will never be run. In the first While loop the Clear is called, but the value is never added back into the ht object. So why is the hashtable cleared when I get the to While m block? Shouldn't this not happen since the Enumerator is readonly?
Thanks in advance for any explanation.
--- Dim ht As New Hashtable()
Dim I As Integer
For I = 1 To 5
Dim h As New Hashtable()
h.Add(I, I) ht.Add(I, h)
Next I
Dim en As IDictionaryEnumerator = ht.GetEnumerator()
While en.MoveNext en.Value.clear() End While
Dim ne As IDictionaryEnumerator = ht.GetEnumerator()
While ne.MoveNext Dim m As IDictionaryEnumerator = ne.Value.GetEnumerator()
While m.MoveNext MsgBox(m.Key & "," & m.Value) End While End While
End Sub
Regards - OHM# On**********@BTInternet.com
Chris,
This seems to be a really bogus example, designed to befuddle the poster and
responder! ;-) While en.MoveNext en.Value.clear() End While
The "en.Value.Clear" is not operating on the Hashtable in the ht variable,
it is calling a method on the class that is referenced in the value
property. (the h Hashtable).
IDictionaryEnumerator is readonly in that you cannot modify the actual
reference returned by the Value, Key, Entry, or Current properties of the
IDictionaryEnumerator variable. You can however modify the objects that
these references refer to!
Remember having a readonly reference does not prevent you from modify the
object that the reference refers to in .NET! It only prevents you from
modifying the reference (field or property) itself.
Try: While ne.MoveNext
MessageBox.Show(ne.Key.ToString() & "," &
ne.Value.ToString())
Dim m As IDictionaryEnumerator = ne.Value.GetEnumerator() While m.MoveNext MsgBox(m.Key & "," & m.Value) End While End While
Also I find its generally better to use GetEnumerator with the For Each
statement, as it producers cleaner & safer code.
Hope this helps
Jay
"Chris Skaryd" <ch***@nospam.skaryd.com> wrote in message
news:ep**************@TK2MSFTNGP10.phx.gbl... Everything I find about IDictionaryEnumerator says that they are readonly.
I'm somewhat confused by the following example. The MsgBox 4 lines from
the bottom will never be run. In the first While loop the Clear is called,
but the value is never added back into the ht object. So why is the hashtable cleared when I get the to While m block? Shouldn't this not happen since
the Enumerator is readonly?
Thanks in advance for any explanation.
--- Dim ht As New Hashtable()
Dim I As Integer
For I = 1 To 5
Dim h As New Hashtable()
h.Add(I, I) ht.Add(I, h)
Next I
Dim en As IDictionaryEnumerator = ht.GetEnumerator()
While en.MoveNext en.Value.clear() End While
Dim ne As IDictionaryEnumerator = ht.GetEnumerator()
While ne.MoveNext Dim m As IDictionaryEnumerator = ne.Value.GetEnumerator()
While m.MoveNext MsgBox(m.Key & "," & m.Value) End While End While
End Sub This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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