While your sentence can be true until we get to defining “expert”, the problem is that there are not going to be many experts if to be an expert at C, one has t

While your sentence can be true until we get to defining “expert”, the problem is that there are not going to be many experts if to be an expert at C, one has to be able to write useful code that does not accidentally invoke undefined behavior. - these four bug reports in NTP are for undefined behaviors. You can say that the NTP maintainers are not experts, the problem is that they are the maintainers of NTP: http://bugs.ntp.org/buglist.cgi?emailreporter2=1&emailtype2=substring&emailcc2=1&query_format=advanced&email2=trust-in-soft&product=ntp http://bugs.ntp.org/buglist.cgi?emailreporter2=1&emailtype2=... - a famous undefined behavior was found in OpenSSL recently, but there were and remain plenty more. Sure, the authors of OpenSSL aren't experts, the problem is, they are the people writing and maintaining OpenSSL. - The Linux kernel has had its share of undefined behaviors. Usually, the developers blame it on the compiler, of which the kernel admits only one (GCC—at least as of recently). There was the time when GCC was blamed for taking advantage of strict aliasing rules, and there was GCC removing of a NULL test on an execution path that dereferenced NULL. If the developers wrote for more compilers, they would realize that the optimizations practiced by GCC are practiced by other compilers too, because they are justified by undefined behavior in the source code. - I could go on. I have quoted three useful, widely deployed C pieces of software that have contained undefined behavior, and likely still contain more. Can you name one nontrivial C program, written by an expert according to your definition, that you are confident does not invoke undefined behavior?