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match_results size() in C++ STL
In this article we will be discussing the working, syntax and examples of match_results::size() function in C++ STL.
What is a match_results in C++ STL?
std::match_results is a specialized container-like class which is used to hold the collection of character sequences which are matched. In this container class a regex match operation finds the matches of the target sequence.
What is match_results::size()?
match_results::size() function is an inbuilt function in C++ STL, which is defined in <regex> header file. size() is used to get the number of matches of the match_results object associated with it. This function returns a size_type value that is the number of matches and sub-matches are there in the object associated with the function.
Syntax
smatch_name.size();
Parameters
This function accepts no parameters.
Return value
This function returns size_type size or the number of the matches and sub matches of the match_results object.
Example
Input: string str = "Tutorials Point";
regex R("(Tutorials)(.*)");
smatch Mat;
regex_match(str, Mat, R);
Mat.size();
Output: 3Example
#include <bits/stdc++.h>
using namespace std;
int main() {
string str = "Tutorials Point";
regex R("(Tutorials)(.*)");
smatch Mat;
regex_match(str, Mat, R);
cout<<"Size is: " << Mat.size() << endl;
return 0;
}Output
If we run the above code it will generate the following output −
Size is: 3
Example
#include <bits/stdc++.h>
using namespace std;
int main() {
string str = "Tutorials Point Tutorials";
regex R("(Tutorials)(.*)");
smatch Mat;
regex_match(str, Mat, R);
for (int i = 0; i < Mat.size(); i++) {
cout <<"length of "<<Mat.length(i)<< endl;
}
return 0;
}Output
If we run the above code it will generate the following output −
length of 25 length of 9 length of 16
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