复选框中的C＃

Question

How to check the box dynamically without firing check changed function? I have 20 checkboxes that are dynamically created and I have a drop-down that determines how many checkboxes are to be checked.

If I selected 3 and click on 6th check box, that should check checkboxes 9, 7 and 8. In this process I don't want to fire checkchanged function.

CheckBox cb1 = (CheckBox)sender;
selectedbox = int.Parse(cb1.Name);

for (int i = 1; i < selectedquantity; i++)
{
    premiumticket[selectedbox].Checked = true; 
    //here check changed firing  i dont want that
    selectedbox++;
}

Answer 1

You can't stop CheckBox from firing event when it's state changed. Consider to either unsubscribe from event when you don't need it:

for (int i = 0; i < selectedquantity; i++)
{
     premiumticket[selectedbox + i].CheckedChanged -= checkBox_CheckedChanged;
     premiumticket[selectedbox + i].Checked = true;
     premiumticket[selectedbox + i].CheckedChanged += checkBox_CheckedChanged;
}

or use some flag to omit handling of event if you don't need it:

flag = false;

for (int i = 0; i < selectedquantity; i++)    
     premiumticket[selectedbox + i].Checked = true;         

flag = true;

And in handler:

private void checkBox_CheckedChanged(object sender, EventArgs e)
{
    if (!flag)
       return;

    //...
}

Answer 2

I can't see really solution how not to fire the event. You could disable the event with -= and then add it again with +=.

 checkBox.CheckedChanged -= checkBox_CheckedChanged;
 checkBox.Checked = true;
 checkBox.CheckedChanged += checkBox_CheckedChanged;

The big disadvantag of this is that you would have to fire the event manually if you would like to have this event once, when you're updating the values.

I'd rather set a flag in the class and check this flag in the update code.

Answer 3

Remove the event attached then attach it after the you change the check :

{
    cb1.CheckedChanged -= new EventHandler(cb1_CheckedChanged);
    premiumticket[selectedbox].Checked = true;
    cb1.CheckedChanged += new EventHandler(cb1_CheckedChanged);
}



private void cb1_CheckedChanged(object sender, EventArgs e)
{
                // Some COde
}

Answer 4

Re-subscribing (unsubscribing/subscribing) technique is not very nice, because you have to deal with every event handler, making it common, adding flags, etc.

What is really simple to do is to use another event - Click - to simply check changes to the control which are made by user :

    private void checkBox1_Click(object sender, EventArgs e)
    {
        checkBox2.Checked = checkBox1.Checked;
        checkBox3.Checked = false;
    }
    private void checkBox2_Click(object sender, EventArgs e)
    {
        // this is not called when you set "Checked" programmatically
    }

It is obvious, what you have to implement different pattern, to actually do something with data (save them or react on changes), if they are changed programmatically. In above example, clicking checkBox2 will run handler, where you, to example, save something into configuration, while setting checkBox2.Checked = true , when clicking checkBox1 , will not.

It may happens, what for some CheckBox 'es you will use only Click , for others - only CheckedChanged .