Brian Hall (aka Beej) has written or collected guides to several programming languages including one on C. Out of curiosity I pasted the one document HTML version into both Word and a text editor to get a feel for how big it is and it filled 416 pages on Word, almost 13,700 lines in a text editor.

It is quite comprehensive covering most aspects of C. He has a disclaimer that its a work in practice and there may be bits that need correcting but still, if you are looking for an excellent guide to C, I’d definitely recommend it and if you like it, send him a tip on Paypal.