 should contain a valid regular expression. You can imbue a <a class="link" href="regex_compiler.html" title="Struct template regex_compiler">regex_compiler</a> object with a locale, after which all <a class="link" href="basic_regex.html" title="Struct template basic_regex">basic_regex</a> objects created with that <a class="link" href="regex_compiler.html" title="Struct template regex_compiler">regex_compiler</a> object will use that locale. After creating a <a class="link" href="regex_compiler.html" title