make_reverse_iterator Function in C++

regex_iterator() function in C++ STL

Last Updated : 26 Oct, 2018

regex_iterator() is a function from the BiDirectionalIterator class in C++. This method returns an iterator type to iterate over different matches of a same regex pattern in a sequence.

Syntax:

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

C++14 Syntax

template <class BidirectionalIterator,
          class charT=typename iterator_traits::value_type,
          class traits=regex_traits > class regex_iterator;

C++11 Syntax:

template <class BidirectionalIterator,
          class charT=typename iterator_traits::value_type,
          class traits=regex_traits > class regex_iterator;

Parameters: This method accepts following parameters:

BidirectionalIterator: Which iterates on the target sequence of characters.
CharT: It is a type char.
traits: It is the regex traits type.

Return Value: This method returns a string object with the resulting sequence.

Below examples illustrate the regex_iterator() method:

Example:

#include <iostream> 
#include <iterator> 
#include <regex> 
#include <string> 
using namespace std; 
  
int main() 
{ 
    const string 
        strg 
        = "Geeksforgeeks welcome geeks."; 
  
    regex words_regex("[^\\s]+"); 
    auto
        words_begin 
        = sregex_iterator( 
            strg.begin(), 
            strg.end(), 
            words_regex); 
  
    auto words_end = sregex_iterator(); 
  
    cout << "Trying to find words"
         << " using regex_iterator:\n\n"; 
  
    cout << "Number of words found: "
         << distance(words_begin, words_end); 
  
    cout << "\n\nThe words are:\n"; 
    for (sregex_iterator k = words_begin; 
         k != words_end; 
         ++k) { 
  
        smatch match = *k; 
        string match_str = match.str(); 
  
        cout << match_str 
             << endl; 
    } 
} 

Output:

Trying to find words using regex_iterator:

Number of words found: 3

The words are:
Geeksforgeeks
welcome
geeks.

make_reverse_iterator Function in C++

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