The development about VST Effect

After audacity update to 2.1.0,“Apply” button which function called?

Are you using Windows? If so, which version?

What effect are you trying to use?

This part of the manual might help:

Windows7 vst Effect audacity2.1.0

The version of Windows is Windows 7 Jpannese.
The Version of VST is VST 2.4.
The development tool is Microsoft Visual Studio 2012.

I’m not sure that I understand your question.
When you press the Apply button, the effect is applied to the current selection. Is that what you are asking?

I am sorry that what I want to know is that when we develop the VST Effect with the tool of
Audacity2.1.0 , Microsoft Visual Studio 2012 and VST2.4, when we press the “Apply” button
debuging with Microsoft Visual Studio 2012 , we can not know the “Apply” button called which
functions in VST2.4, so the VST Effect was not used.

Which “Apply button” are you pressing? Are you referring to a button in MSVS?
Is your question about programming?
Are you trying to write a VST plug-in effect?

Yes, I am writting the program of a VST plug-in Effect.
Now, I don not know where I shoud ask the question about programing?
Can you help me?

I have moved this topic to the “General Audio Programming” forum.

We may not be able to offer much help on this forum, as the focus of the forum is about helping people to use Audacity.
I have some programming experience, but I don’t use Windows, so I don’t use MSVS or VST.

Audacity is probably not the ideal platform for developing VST effects as we do not use the Steinberg VST headers (due to licensing restrictions).
If you specifically want to develop VST plug-ins, you may find it easier to develop on a VST host that has full support for Steinberg VST.