variables undeclared

Hi I have experienced an error in my code which states that the variables are not declared in setup. However, I have actually declared them in the other files which I have added into the same .ino file. As the files that I have added in as libaries are .cpp files, I am wondering if Arduino doesn't recognise the language and hence the variables are not declared?

I have experienced an error in my code

Which strangely, you have omitted to post.

I am wondering if Arduino doesn't recognise the language and hence the variables are not declared?

Wonder no more, cpp is a valid file type for the arduino IDE.

As the files that I have added in as libaries

So are these libraries in the right place?
Have you put an #include in the code?
Have you restarted the IDE since you installed the libraries?