Question

    namespace explorer
    {
        public partial class Form1 : Form
        {
            public Form1()
            {
                InitializeComponent();
                DirectoryInfo di = new DirectoryInfo("c:\\test");
                FileSystemInfo[] files = di.GetFileSystemInfos();
                checkedListBox1.Items.AddRange(files);
            }

            private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
            {
                for (int ix = 0; ix < checkedListBox1.Items.Count; ++ix)
                if (ix != e.Index) checkedListBox1.SetItemChecked(ix, false); 
            }
            //removed irrelevant parts of the code
        }
    }

I forgot how to build an event handler for the checkedlistbox.
I need one selected. I have multiple files but I need just one selected by a check box.

Answer 1

You need to turn off the event handler or use a variable as a flag to avoid a stack overflow since you are unchecking items in an ItemCheck event:

private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {
  checkedListBox1.ItemCheck -= checkedListBox1_ItemCheck;
  for (int ix = 0; ix < checkedListBox1.Items.Count; ++ix) {
    if (ix != e.Index) {
      checkedListBox1.SetItemChecked(ix, false);
    }
  }
  checkedListBox1.ItemCheck += checkedListBox1_ItemCheck;
}

An example using a variable:

bool checkFlag = false;

private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {
  if (!checkFlag) {
    checkFlag = true;
    for (int ix = 0; ix < checkedListBox1.Items.Count; ++ix) {
      if (ix != e.Index) {
        checkedListBox1.SetItemChecked(ix, false);
      }
    }
    checkFlag = false;
  }
}