Reputation: 41128

How can I use a foreach loop to delete all of the control in a panel?

Here's the code I have:

private void ClearSearchResults()
    {
        foreach (Control X in panel1.Controls)
        {
            panel1.Controls.Remove(X);
        }
    }

The problem is, when I run this method, only a single item is deleted, then if I click on a button again so the method can run again, another is deleted.

If I have 10 control in my panel, I'd have to click the "Delete" button on my program many times for all the control to be deleted.

What can I do in this case?

Upvotes: 4

Answers (10)

mesteru_vali

Reputation: 11

while (panel1.Controls.Count != 0)
{
    foreach (Control c in panel1.Controls)
    {
        panel1.Controls.Remove(c);
    }
}

Another way !

Upvotes: 0

Tarik

Reputation: 81711

Actually you can't use Remove because it breaks the iterator so simple solution would be something like this :

var controls = in c from panel1.Controls select c;
foreach(Controls _control in controls)
{
   panel1.Controls.Remove(_control);
}

but of course you don't want to stick to Loop then go ahead and use panel1.Controls.Clear()

Upvotes: 0

JonH

Reputation: 33143

            int n;
            n = panel1.Controls.Count-1;

            for (int i = 0; i <= n; i++ )
            {
                Control c = panel1.Controls[0];
                panel1.Controls.Remove(c);
            }

Upvotes: 0

Austin Salonen

Reputation: 50215

Does this work for you?

private void ClearSearchResults()
{
    panel1.Controls.Clear();
}

Edited to emphasize the CKret comment.

Upvotes: 14

Crash893

Reputation: 11702

  private void ClearSearchResults()
        {
            foreach (Control X in panel1.Controls)
            {
                panel1.Controls.Remove(X);
            }
            if (panel1.Controls.Count > 0)
            { 
                ClearSearchResults();
            }
        }

Upvotes: 0

djdd87

Reputation: 68456

For a start you shouldn't edit the IEnumerable collection within a foreach loop. You should be using a for loop or a while.

I.e.

private void ClearSearchResults()
    {
        while (panel1.Controls.Count > 0)
        {
            panel1.Controls.RemoveAt(0);
        }
    }

or just use:

 panel1.Controls.Clear();

Upvotes: 3

Reed Copsey

Reputation: 564383

You, in general, can't remove from a collection while iterating an enumerable generated from it. Instead of using foreach, the typical approach is to use a for loop working backwards:

private void ClearSearchResults()
{
    for(int i=panel1.Controls.Count-1;i>=0;--i) {
        panel1.Controls.RemoveAt(i);        
        // or
        // Control X = panel1.Controls[i];
        // panel1.Controls.Remove(X);
    }
}

However, in this case, just use clear: