https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63227
Tim Shen <timshen at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |timshen at gcc dot gnu.org --- Comment #1 from Tim Shen <timshen at gcc dot gnu.org> --- Assertions "\\A" and "\\z" are not supported by C++11 regex's default syntax regex_constants::ECMAScript. Using const NS::regex e("\\b(\\d{3,4})[- ]?(\\d{4})[- ]?(\\d{4})[- ]?(\\d{4})\\b"); can get expected result.