C# 复选框选中计数

Question

I have several checkboxes and a button inside a panel, that is inside a tabPage, inside a WinForm C# application.

What I am trying to do is making sure at least one checkbox is checked so enable the button to be clickable, if not the button will be disabled (gray display non-clickable).

I tried this (in Form_Load event) but it didn't work:

int counter = 0;
        foreach (Control p in tabPage1.Controls)
        {
            if (p is Panel)
            {
                foreach (Control c in panel1.Controls)
                {
                    if (c is CheckBox)
                    {
                        if (((CheckBox)c).Checked)
                        {
                            counter++;
                        }
                        if (counter < 1)
                        {
                            button1.Enabled = false;
                        }
                        else
                        {
                            button1.Enabled = true;
                        }
                    }
                }
            }
        }

It's either because I am using the wrong event or the wrong place to put the code, or the code itself isn't correct, can anyone take a look please?

Answer 1

You can do something like this (note.. your specific loops are redundant.. you know the name of the container.. why loop searching for it?)

if (panel1.Controls.OfType<CheckBox>().Any(x => x.Checked)) {
    // at least one is checked..

Answer 2

This code should be run in two places:

• The form's Load event, after you've loaded the checkboxes with any saved values
• The checkboxes' CheckedChanged event handlers, so the button state is updated as checkboxes are checked

Answer 3

Remove this part you never use "p" variable in your code below...

foreach(Control p in tabPage1.Controls)
{
  if (p is Panel)
  {

int counter = 0;
foreach(Control c in panel1.Controls)
{
  if (c is CheckBox)
  {
    if (((CheckBox)c).Checked)
    {
      counter++;
    }
    if (counter < 1) {
      button1.Enabled = false;
    }
    else {
      button1.Enabled = true;
    }
  }
}