How do I get the version of an assembly without loading it?

Question

One small function of a large program examines assemblies in a folder and replaces out-of-date assemblies with the latest versions. To accomplish this, it needs to read the version numbers of the existing assembly files without actually loading those assemblies into the executing process.

Answer 1

Use AssemblyName.GetAssemblyName("assembly.dll");, then parse the name. According to MSDN:

This will only work if the file contains an assembly manifest. This method causes the file to be opened and closed, but the assembly is not added to this domain.

Answer 2

I found the following in this article.

using System.Reflection;
using System.IO;

...

// Get current and updated assemblies
AssemblyName currentAssemblyName = AssemblyName.GetAssemblyName(currentAssemblyPath);
AssemblyName updatedAssemblyName = AssemblyName.GetAssemblyName(updatedAssemblyPath);

// Compare both versions
if (updatedAssemblyName.Version.CompareTo(currentAssemblyName.Version) <= 0)
{
    // There's nothing to update
    return;
}

// Update older version
File.Copy(updatedAssemblyPath, currentAssemblyPath, true);

Answer 3

Depending on the files, one option might be FileVersionInfo - i.e.

FileVersionInfo fvi = FileVersionInfo.GetVersionInfo(path)
string ver = fvi.FileVersion;

The problem is that this depends on the code having the [AssemblyFileVersion] attribute, and it matching the [AssemblyVersion] attribute.

I think I'd look at the AssemblyName options suggested by others first, though.