Selecting multiple Listbox items through code

Question

Hi there I have searched for a while now and can't seem to find a solution to my problem, I have tried multiple methods to select multiple items in my listbox through code however none have worked, The best result I got was 1 selected item in my listbox.

Basically I want to select multiple items of the same value.

below is my code, sorry if I seem newbie but I am new to programming and still learning basic stuff.

 foreach (string p in listBox1.Items)
 {
           if (p == searchstring) 
           {
                 index = listBox1.Items.IndexOf(p);
                 listBox1.SetSelected(index,true);

           }
 }

So as you can see I am trying to tell the program to loop through all the items in my listbox, and for every item that equals "searchstring" get the index and set it as selected.

However all this code does is select the first item in the list that equals "searchstring" makes it selected and stops, it doesn't iterate through all the "searchstring" items.

Answer 1

As suggested in the comment, you should set SelectionMode to either MulitSimple or MultiExpanded depending on your needs, but you also need to use for or while loop instead offoreach, because foreach loop doesn't allow the collection to be changed during iterations. Therefore, even setting this Property won't make your code run and you will get the exception. Try this:

for(int i = 0; i<listBox1.Items.Count;i++)
{
     string p = listBox1.Items[i].ToString();
     if (p == searchstring)
     {
          listBox1.SetSelected(i, true);

     }
}

You can set SelectionMode either in the Properties window when using designer or in, for instance, constructor of your Form using this code:

listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiSimple;