Im using a hashtable to hold all my connected clients, I have a loop statment that sends data to each client to make sure there all connected and im using a foreach statment to go through the hashtable to fet the clients name to send the data. now if the server cant send the data to a client it will remove the client name from the hashtable, when the code loops through again I get a error saying the collection was modified if I click continue the loop will exit. how can I fix this little problem
foreach
Hot Topic
Visual C#
- C# Equivalent of SqlDataReader.Item
- FAXCOMLib
- How do you change the value of an already created cookie?
- Why should we have to declare the delegate in both places
- "There is no source code available for the current location"
- Need Tips on finding information (Vikram)
- How can overloaded operator access private fields of another class
- List the names of "folders and files" under a directory in a treeView control???
- Login Screen
- Help ( i mean it) lol
foreach
Sunil_pachunde
did you try to exit the loop after deleting a entry and to go in afterwards again
You may replace the foreach statement by a for statement that cycles throug the list. But remember after deleting something from your table you should decrement your count-variable, otherwise you skipe an element
Mikaelm
You could keep another Hashtable of inactive clients and then remove these after iterating over the client list.
Hashtable clients = new Hashtable();
// whatever fills the client hashtable
// before iterating over clients ensure you have
// an empty inactive client table
Hashtable inactiveClients = new Hashtable();
foreach (DictionaryEntry client in clients)
{
// communicate with client
// if communication fails add them to the inactive list
inactiveClients.Add(client.Key, client.Value);
}
// now remove the inactive clients
foreach (DictionaryEntry inactiveClient in inactiveClients)
{
clients.Remove(inactiveClient.Key);
}
If you don't need the client "value" for removal you could use an ArrayList to keep track of the inactive clients. Here's code for when your Hashtable keys are simple strings:
// before iterating over clients ensure you have
// an empty inactive client list
ArrayList inactiveClients = new ArrayList();
foreach (DictionaryEntry client in clients)
{
// communicate with client
// if communication fails add them to the inactive list
inactiveClients.Add(client.Key);
}
// now remove the inactive clients
foreach (string inactiveClient in inactiveClients)
{
clients.Remove(inactiveClient);
}
(Code was not pasted from IDE so there could be syntax errors)
QuanT
Hashtables do not allow you get values by index, so using a for loop as Ralph suggested will not help.
If a collection gets modified during a foreach (or a enumeration), then a InvalidOperationException will be thrown. To get around this, you could create a 'snapshot' of the Hashtable and then perform a foreach on it:
Hashtable clients = new Hashtable();
....
Hashtable snapshot = new Hashtable(clients);
foreach (DictionaryEntry entry in snapshot)
{
...
}