match_results size() in C++ STL

The match_results size() is a inbuilt function in C++ which returns the number of matches ans sub-matches in the match_result object.

Syntax:

smatch_name.size()

Note: smatch_name is an object of match_results class.

Parameters: The function accept no parameters.

Return vaulue: It returns the number of matches in the match_result object.

Note: First element always contains the whole regex match while the others conatain the particular Capturing Group



Below programs illustrate the above function.

Program 1:

filter_none

edit
close

play_arrow

link
brightness_4
code

// CPP program to illustrate
// match_results size() in C++
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    string s("Geeksforgeeks");
    regex re("(Geeks)(.*)");
  
    smatch match;
  
    // Function call to find match
    regex_match(s, match, re);
  
    cout << "match size is " << match.size() << endl;
  
    return 0;
}

chevron_right


Output:

match size is 3

Program 2:

filter_none

edit
close

play_arrow

link
brightness_4
code

// CPP program to illustrate
// match_results size() in C++
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    string s("Geeksforgeeks");
    regex re("(Geeks)(.*)");
  
    smatch match;
  
    // Function call to find matches
    regex_match(s, match, re);
  
    cout << "match size is " << match.size() << endl;
  
    for (int i = 0; i < match.size(); i++) {
        cout << "match " << i << " has a length of "
             << match.length(i) << endl;
    }
    return 0;
}

chevron_right


Output:

match size is 3
match 0 has a length of 13
match 1 has a length of 5
match 2 has a length of 8


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.