I think this is an excellent introduction to what makes C different than most modern high level languages:http://www.chiark.gr.../~sgtatham/cdescent/
This article attempts to give a sort of ‘orientation tour’ for people whose previous programming background is in high (ish) level languages such as Java or Python, and who now find that they need or want to learn C.
C is quite different, at a fundamental level, from languages like Java and Python. However, well-known books on C (such as the venerable Kernighan & Ritchie) tend to have been written before Java and Python changed everyone's expectations of a programming language, so they might well not stop to explain the fundamental differences in outlook before getting into the nitty-gritty language details. Someone with experience of higher-level languages might therefore suffer a certain amount of culture shock when picking up such a book. My aim is to help prevent that, by warning about the culture shocks in advance.
This article will not actually teach C: I'll show the occasional code snippet for illustration and explain as much as I need to make my points, but I won't explain the language syntax or semantics in any complete or organised way. Instead, my aim is to give an idea of how you should expect C to differ from languages you previously knew about, so that when you do pick up an actual C book, you won't be distracted from the details by the fundamental weirdness.