How to build a DLL with custom file extension in a C# project?

Question

Is there any way to compile a C# DLL project (visual studio) into a file with a custom extension? for example plugin.cpx instead of plugin.dll (cpx = C ustom P lugin e X tension!)

And can I use any extension I want?

Answer 1

^{I'm adding this as a new answer because it is just that. And it's a lot easier than my earlier offering, in many ways.}

You can explicitly specify the target extension by manually editing the project's .csproj file.

In "Solution Explorer," right click on the project and select the "Unload project" command. Then, right-click again and select "Edit MyProject.csproj" (where "MyProject" would be the actual name, obviously).

To make the extension change apply to all configurations and/or platforms, add the following three lines, near the top of the file (just before the first of the other PropertyGroup entries):

  <PropertyGroup>
    <TargetExt>.cpx</TargetExt>
  </PropertyGroup>

Then save the file, close it, and "Reload" the project (again, via a right-click in the Solution Explorer).

To change the extension only for a specific configuration or platform, add the TargetExt line inside the PropertyGroup relevant to that configuration.

Answer 2

And can I use any extension I want?

Yes, you can, but it's a bit 'tricky'.

For C# projects, you will need to add a custom "Post Build Event" to rename the output file. For a DLL project (as yours is) you can add a post-build command like that shown below, in the "Build Events" tab of the "Properties" window:

Note: Be sure to use the $(TargetName) macro, not $(TargetFileName) , as the latter will implicitly include the .dll extension. But you could use:

rename "$(TargetDir)$(TargetFileName)" "$(TargetName).cpx"

EDIT: Also, you will need to tell the builder to delete any old version of the .cpx file, at some stage. This could be done as a pre-build event, as follows:

IF EXIST "$(TargetDir)$(TargetName).cpx" del "$(TargetDir)$(TargetName).cpx"

Without this, the attempt to rename the output file will fail (as the new 'target' will already exist).

EDIT-2: As noted in the comment by the OP, without the " quotes, the pre- and post-build commands will fail if there are spaces in the file paths.