Question

How do I filter items in a listbox using a combobox using c# and windows forms?

the listbox contains files and the combobox needs to filter them by their extension

Please help I’m new to programming

Answer 1

This is almost an exact duplicate from your last question. The same answer applies.

On the selected index changed event of the combo box, I’d add the items to your listbox based off of the filter selected from your combobox. You can use System.IO.DirectoryInfo to filter your directory given a file extension.

//Clear your listBox before filtering if it contains items
if(yourListBox.Items.Count > 0)
   yourListBox.Items.Clear();
DirectoryInfo dInfo = new DirectoryInfo(<string yourDirectory>);                                 
FileInfo[] fileInfo = dInfo.GetFiles("*" + <string yourChosenFileExtension>);
foreach (FileInfo file in fileInfo)
{  
   yourListBox.Items.Add(file.Name);
}

Filtering a texbox with a combobox