How to: Determine If a File Is an Assembly (C# and Visual Basic)
A file is an assembly if and only if it is managed, and contains an assembly entry in its metadata. For more information on assemblies and metadata, see the topic Assembly Manifest.
How to manually determine if a file is an assembly
How to programmatically determine if a file is an assembly
This example tests a DLL to see if it is an assembly.
Module Module1 Sub Main() Try Dim testAssembly As Reflection.AssemblyName = Reflection.AssemblyName.GetAssemblyName("C:\Windows\Microsoft.NET\Framework\v3.5\System.Net.dll") Console.WriteLine("Yes, the file is an Assembly.") Catch ex As System.IO.FileNotFoundException Console.WriteLine("The file cannot be found.") Catch ex As System.BadImageFormatException Console.WriteLine("The file is not an Assembly.") Catch ex As System.IO.FileLoadException Console.WriteLine("The Assembly has already been loaded.") End Try Console.ReadLine() End Sub End Module ' Output (with .NET Framework 3.5 installed): ' Yes, the file is an Assembly.
The GetAssemblyName method loads the test file, and then releases it once the information is read.