试图在单击单个复选框时在选中的列表框中选择所有项目

Question

I'm trying to select all items in checked list box when check box All is checked" How to get that, here is my code

private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
    if (cbAll.Checked)
    {
        if(clbViruslist.Items.Count > 0)
        {
           // here clbViruslist is the checked list o
           // for(int i=0;i<clbViruslist.Items.Count;i++)
           // clbViruslist.SetSelected(i,true);
           // clbViruslist.SetSelected(0,true ) ;
        }
     }
 }

Answer 1

private void cbAll_CheckedChanged(object sender, EventArgs e)
    {
        if (cbAll.Checked)
        {
            foreach (ListItem item in clbViruslist.Items)
            {
                item.Selected = true;                
            }
        }
    }

or this is much better

private void checkBox1_CheckedChanged(object sender, EventArgs e)
    {
       foreach (ListItem item in clbViruslist.Items)
       {
           item.Selected = checkBox1.Checked;                
       }

    }

Answer 2

Handle the CheckedChanged event of 'Select All' checkBox. In this, loop through all the items of checkedListBox and check them.

private void checkBoxAll_CheckedChanged(object sender, EventArgs e)
{
    if (checkBoxAll.Checked)
        for (int i=0; i <= clbViruslist.Items.Count; i++)
            clbViruslist.SetItemChecked(i, true);
}

If you want to uncheck all checkedListBox items on unchecking the 'Select All' checkbox, use this:

private void checkBoxAll_CheckedChanged(object sender, EventArgs e)
{
    if (checkBoxAll.Checked)
        for (int i=0; i <= clbViruslist.Items.Count; i++)
            clbViruslist.SetItemChecked(i, true);
    else
        for (int i=0; i <= clbViruslist.Items.Count; i++)
            clbViruslist.SetItemChecked(i, false);
}

You may also want to uncheck the 'Select All' checkBox, if any of the checkedListBox items is unchecked. For this, handle the ItemCheck event of checkedListBox and uncheck 'Select All' checkBox if any of the items is unchecked.