C11 says: (C11, 7.24.2.1p2) “The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1.” &a + 1 itself is a valid pointer to integer addition but &a + 1 is not a pointer to an object, so the call invokes undefined behavior.
regex_match only returns true when the entire input sequence has been matched, while regex_search will succeed even if only a sub-sequence matches the regex. Quoting from N3337, ยง28.11.2/2 regex_match [re.alg.match] Effects: Determines whether there is a match between the regular expression e, and all of the character sequence [first,last). … Returns true if such a … Read more
This is more a framework for adding such checks than an attempt to detect all forms of undefined behavior (which is almost certainly impossible in the “halting problem” sense). The GCC documentation lists these as the currently supported checks: -fsanitize=undefined Enable UndefinedBehaviorSanitizer, a fast undefined behavior detector. Various computations will be instrumented to detect undefined … Read more
GCC 4.9 introduces a newer C++ ABI version than your system libstdc++ has, so you need to tell the loader to use this newer version of the library by adding that path to LD_LIBRARY_PATH. Unfortunately, I cannot tell you straight off where the libstdc++ so for your GCC 4.9 installation is located, as this depends … Read more