All of files in this folder are PDF files

[fenglish]

Hi,

There are lots of PDF files in directory "D:\PDF_Folder".

A. All files in this folder are PDF files.
B. All of files in this folder are PDF files.

Are both A and B correct?
I had used "All files" and "All of files" and similar in some technical documents, now I need to find the exact difference between them.
Please help, thanks.

 

[Matthew Wai]

I consider B incorrect because 'the' is missing before 'files'.

 

[SoothingDave]

The final "files" is a bit redundant. In real life, you would hear "are pdfs."

 

[fenglish]

Why is the "the" required?

A. All of the books ...
B. All of the peoples ...
C. All of the "[any noun]"s ...

D. All of books ...
E. All of peoples ...
F. All of "[any noun]"s ...

Based on the answer, then, ABC is correct, DEF is incorrect, right? Is it applied to all situation?

 

[MikeNewYork]

Pretty much all common nouns require an article.

 

[Matthew Wai]

Why is the "the" required?

I think it is because you are referring to the specific files in the folder rather than unspecified ones.

 

[Tdol]

The final "files" is a bit redundant. In real life, you would hear "are pdfs."

And you might see PDFs.