Check if a file exists in .NET with C# / VB

Once you've checked if a folder exists, determine if a file itself exists, or needs to be created. Start by making sure that the System.IO namespace is included at the top of your code: using System.IO;
When dealing with file paths, either escape all backslashes ("\"), or prepend the "@" symbol before the opening double quote to use string literals. Here's the same file path, declared both ways: string file = "C:\\Projects\\Notes\\file.txt"; // escape all backslashes string file = @"C:\Projects\Notes\file.txt"; // or use a string literal
Now check if the file exists, by supplying the full path: boolean True or False is returned.if( File.Exists( file ) ) // Proceed with file handling code... else MessageBox.Show("This file doesn't exist!");
You can also re-use your file variable to check the file size: (returned in bytes). long fileSize = new FileInfo( file ).Length; If the file doesn't exist, create it -optionally writing some content to it- but avoid using it for a few milliseconds. If needed, use a timer before reading from it.
Note: aside from Length, other useful attributes you can get the same way (without actually opening the file) include CreationTime, IsReadOnly, LastAccessTime and LastWriteTime.

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