Find files listing by extension in .NET with C# or VB

In .NET, getting a list of all files with a particular extension inside a directory (and optionally in its subfolders as well) is a breeze. The process works similarly in C# and VB. Include System.IO: using System.IO; // Include namespace at top of project
Tip: to program defensively, check first if the folder exists (or currently available on the network).
The collection of matching files is returned as a string array: // Use '@' for C# string literals to avoid escaping backslashes (n/a for VB) string folder = @"C:\Projects\Notes"; string[] textFiles = Directory.GetFiles( folder, ".txt" ); MessageBox.Show( "Found " + textFiles.Length.ToString() + " text files" );
Note: the file extension filter is case-insensitive (passing *.txt yields same listing as *.TXT).
To search for files only in the folder supplied (not sub-directories), pass this search option: Directory.GetFiles( folder, ".TXT", SearchOption.TopDirectoryOnly );
By default, the full path is included (C:\Projects\Notes\File.txt). Just use the Substring() method when using these file names. This snippet populates a dropdown with file names without full path: string name = ""; for( int i=0; i < textFiles.Length; ++i ) { name = textFiles[i].Substring( textFiles[i].LastIndexOf("\\")+1 ); dropdown.Items.Add( name ); }
Tip: to hide file extensions, append .Replace( “.txt”, “” ) after the assignment to name (line 3).

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