They are called undefined behaviors because the compiler developers are free to do whatever they want when they come across a code that instigates an undefined

They are called undefined behaviors because the compiler developers are free to do whatever they want when they come across a code that instigates an undefined behavior. Mostly new compilers now a days do handle such behavior with a compiler error or warning. So if you try to do an out of bound shift a new compiler might throw a warning, but according to the C standard it does not have to. In fact instead of throwing a warning it can wipe your complete hardware and that too is allowed according to the C standard... In contrast there is implementation defined behavior, and unspecified behavior. Where the compiler developers have to document and take care of certain things. I wrote a detailed article about the subtle difference you can check that out.... https://medium.com/@faizan10114/understanding-c-terminologies-a-dummies-perspective-695af2648289 https://medium.com/@faizan10114/understanding-c-terminologie...