Class template
sub_match denotes the sequence of characters matched
by a particular marked sub-expression
.namespace std {
template<class BidirectionalIterator>
class sub_match : public pair<BidirectionalIterator, BidirectionalIterator> {
public:
using value_type =
typename iterator_traits<BidirectionalIterator>::value_type;
using difference_type =
typename iterator_traits<BidirectionalIterator>::difference_type;
using iterator = BidirectionalIterator;
using string_type = basic_string<value_type>;
bool matched;
constexpr sub_match();
difference_type length() const;
operator string_type() const;
string_type str() const;
int compare(const sub_match& s) const;
int compare(const string_type& s) const;
int compare(const value_type* s) const;
};
}