std::regex_iterator

std::regex_iterator is a read-only iterator that accesses the individual matches of a regular expression within the underlying character sequence. It meets the requirements of a LegacyForwardIterator, except that for dereferenceable values a and b with a == b, *a and *b will not be bound to the same object.

# Declarations

template<
class BidirIt,
class CharT = typename std::iterator_traits<BidirIt>::value_type,
class Traits = std::regex_traits<CharT>
> class regex_iterator

(since C++11)

# Notes

It is the programmer’s responsibility to ensure that the std::basic_regex object passed to the iterator’s constructor outlives the iterator. Because the iterator stores a pointer to the regex, incrementing the iterator after the regex was destroyed accesses a dangling pointer.

If the part of the regular expression that matched is just an assertion (^, $, \b, \B), the match stored in the iterator is a zero-length match, that is, match[0].first == match[0].second.

# Example

#include <iostream>
#include <iterator>
#include <regex>
#include <string>
 
int main()
{
    const std::string s = "Quick brown fox.";
 
    std::regex words_regex("[^\\s]+");
    auto words_begin = std::sregex_iterator(s.begin(), s.end(), words_regex);
    auto words_end = std::sregex_iterator();
 
    std::cout << "Found " << std::distance(words_begin, words_end) << " words:\n";
 
    for (std::sregex_iterator i = words_begin; i != words_end; ++i)
    {
        std::smatch match = *i;
        std::string match_str = match.str();
        std::cout << match_str << '\n';
    }
}

# Defect reports

# See also

• match_results
• regex_search