How to make a standard VKontakte bot response to an unknown command?

Question

PHP

I am writing a bot in php for the VKontakte community. It works through the official Contact API.
There is a list of strictly defined bot commands, but users write different messages to the bot, and he, of course, does not respond to them. Is it possible to create a standard response to such messages using php. The answer should be something like this: the command is unknown
If you can do this, please send an example of use.

Answer 1

Use if/ switch . What is the problem?