Check if a File Exists in C# or VB.Net
File.Exists Method

The File Class provides static methods for the creation, copying, deletion, moving, and opening of a single file. Also it provides a method File.Exists() for checking a File exist or not.
Syntax
The File.Exists method returns a Boolean value.

It will return true if the caller has the required permissions and path contains the name of an existing file, otherwise it will return false. Also passing an invalid path will return returns false
It is easy to check with the conditional operator (?).
Search File using wild card
You can use wild card characters to check a file exists in a folder.
How to check if a file exists in a folder?
Source Code | C#
Source Code | Vb.Net
You can use searchoption enumeration to specifies whether to look in the current directory, or the current directory and all subdirectories.
SearchOption.AllDirectories
SearchOption.AllDirectories includes the current directory and all its subdirectories in a search operation.
SearchOption.TopDirectoryOnly
SearchOption.TopDirectoryOnly includes only the current directory in a search operation.
.Net Framework 4
If you are using Microsoft .Net Framework 4 or above you can use Directory.EnumerateFiles.

This method will be more efficient than using Directory.GetFiles because you can avoid to iterate trough the entire file list.
Check File exist in Network Path
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