match_results length() in C++ STL
The match_results::length() is a inbuilt function in C++ which is used to return the length of a particular match in the match_results object.
Syntax:
smatch_name.length(n)
Note: smatch_name is an object of match_results class.
Parameters: It accepts a single parameter n which specifies the Match number. It is lower than match_results::size. The match number 0 represents the entire matched expression. Subsequent match numbers identify the sub-expressions if any. The passed integral is an unsigned integral type.
Return Value:It returns the length of the n-th match in the match_results object.
Note: First element always contains the whole regex match while the others contain the particular Capturing Group.
Below programs illustrate the above function.
Program 1:
CPP
#include <bits/stdc++.h>
using namespace std;
int main()
{
string s( "Geeksforgeeks" );
regex re( "(Geeks)(.*)" );
smatch match;
regex_match(s, match, re);
for ( int i = 0; i < match.size(); i++) {
cout << "match " << i << " has a length of "
<< match.length(i) << endl;
}
return 0;
}
|
Output:
match 0 has a length of 13
match 1 has a length of 5
match 2 has a length of 8
Program 2:
CPP
#include <bits/stdc++.h>
using namespace std;
int main()
{
string s( "Geeksforgeeks" );
regex re( "(Ge)(eks)(.*)" );
smatch match;
regex_match(s, match, re);
int max_length = 0;
string str;
for ( int i = 1; i < match.size(); i++) {
if (match.length(i) > max_length) {
str = match[i];
max_length = match.length(i);
}
}
cout << "max-length sub match is " << str
<< " with a length of " << max_length;
return 0;
}
|
Output:
max-length sub match is forgeeks with a length of 8
Last Updated :
21 Jun, 2021
Like Article
Save Article
Share your thoughts in the comments
Please Login to comment...