"iam looking to learn C language for programming microcontrollers."

DO you know 'C' already?
Most of the tutorials I've seen seem to be for 'C' programmers who want to know the particular issues with the 8051.

It will, of course, be compiler-dependent to a large degree.

Keil used to include one called "the last word on 8051 programming" or something. It's been mentioned here some time back, so try a search for "last word" - there were links to other sources.

You will need a copy of "The 'C' Programming Language" by Kernighan & Ritchie - usually just called "K&R". This is the definitive reference for The 'C' Programming Language (Messrs Kernighan & Ritchie wrote the language!). Note that I say "reference" - it is not generally a good book from which to learn The 'C' Programming Language.