Oliver Kullmann wrote:
I have the C99 standard (as a book), while the C90 standard (I thought it would be C89?) seems to cost a fortune.
C++ explicitly referes to ISO/IEC 9899:1990 . You may call it C89, I will to consistently call it C90. The point remains that C++ does not refer to any newer version of the C standard.
I believe that C90 that C++ standard referes to, does not mention UB.
But then it should be the case that the C99 standard only makes more precise what the older standard left out?
No. The wording in C90 standard is actually important. It simply leaves this question not-standarized and the C++ standard does not add anything in this respect. However, if (or rather when) C++ is updated to refer to the newer version of the C standard, it will have to be considered. B.