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To add to the others noting the differences between C's behaviour and the underlying assembly, I recommend Chris Lattner's (the creator of LLVM) series of posts

To add to the others noting the differences between C's behaviour and the underlying assembly, I recommend Chris Lattner's (the creator of LLVM) series of posts about Undefined Behaviour in C: http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html http://blog.llvm.org/2011/05/what-every-c-programmer-should-... http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html http://blog.llvm.org/2011/05/what-every-c-programmer-should-... http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_21.html http://blog.llvm.org/2011/05/what-every-c-programmer-should-... (HN truncates the text of the URL, but they're all different) I've been coding C professionally for over a decade, as required for firmware/embedded development, and those posts have instilled the fear of god in me.

exDM69 11y ago
> ... and those posts have instilled the fear of god in me. But why? Yeah, hitting UB can be a terrifying idea but rarely happens in practice. In two decades of C programming, I have hit an UB bug exactly once when a piece of code was ran on an ARM platform for the first time. It took a little bit of staring at disassembly and reading some docs to sort out but it wasn't the end of the world. Understanding the basic cases is a good idea but the darkest corners of undefined behavior are only important if you're a compiler writer like Chris Lattner is.
- jhomedall 11y ago
  A solid understanding of undefined behavior is required if you want to write software in C that is secure, that will behave properly, and that is portable. Undefined behavior has been the source of numerous security exploits in the past, and will only get worse as modern optimizing compilers become more advanced.