c# - How to set filter for FileSystemWatcher for multiple file types?

Question

Everywhere I find these two lines of code used to set filter for file system watcher in samples provided..

FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Filter = "*.txt";
//or
watcher.Filter = "*.*";

But I want my watcher to monitor more file types, but not all. How can I achieve this:

//watcher.Filter = "*.txt" | "*.doc" | "*.docx" | "*.xls" | "*.xlsx";

I tried these:

 watcher.Filter = "*.txt|*.doc|*.docx|*.xls|*.xlsx"; 
 // and
 watcher.Filter = "*.txt;*.doc;*.docx;*.xls;*.xlsx*";

Both did not work. This is just basics but I miss it. Thanks..

Answer 1

You can't do that. The Filter property only supports one filter at a time. From the documentation:

Use of multiple filters such as *.txt|*.doc is not supported.

You need to create a FileSystemWatcher for each file type. You can then bind them all to the same set of FileSystemEventHandler:

string[] filters = { "*.txt", "*.doc", "*.docx", "*.xls", "*.xlsx" };
List<FileSystemWatcher> watchers = new List<FileSystemWatcher>();

foreach(string f in filters)
{
    FileSystemWatcher w = new FileSystemWatcher();
    w.Filter = f;
    w.Changed += MyChangedHandler;
    watchers.Add(w);
}