Regular Expression Objects

Objects of type regular expression are instances of the class template template <class charT, class traits= regex_traits <charT>> class basic_regex parametrized by their character type and traits class. The traits class defines the interpretation of the properties of the regular grammar. There are two type synonyms in C++:

typedef basic_regex<char> regex;
typedef basic_regex<wchar_t> wregex;

You can further customise the object of type regular expression. Therefore you can specify the used grammar or adapt the syntax. As said before, C++ supports the basic, extended, awk, grep and egrep grammars. A regular expression qualified by the std::regex_constants::icase flag is case insensitive. If you want to adopt the syntax, you have to specify the grammar explicitly.

Specify the grammar

// regexGrammar.cpp 
...
#include <regex>
...
using std::regex_constants::ECMAScript;
using std::regex_constants::icase;

std::string theQuestion...