match_results prefix() and suffix() in C++

• The match_results::prefix() is an inbuilt function in C++ which is used to get the string which is preceding the matched string in the input target string.
  Syntax:
  

smatch_name.prefix()

Note: smatch_name is an object of match_results class.

• Parameters: This function accept no parameters.
  Return Value: This function returns the sequence preceding the matched sequence in the target string.
  Note: First element always contains the whole regex match while the others contain the particular Capturing Group.
  Below program illustrate the above function: 
  

CPP

// CPP program to illustrate
// match_results prefix() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    string s("Geeksforgeeks is a computer science portal");
    regex re("computer");

    smatch match;

    regex_search(s, match, re);

    cout << "Prefix is: [";
    if (!match.empty()) {
        cout << match.prefix() << "]" << endl;
    }
    return 0;
}

Output:

Prefix is: [Geeksforgeeks is a ]

• The match_results::suffix() is an inbuilt function in C++ which is used to get the string which is succeeding the matched string in the input target string.
  Syntax:
  

smatch_name.suffix()

Note: smatch_name is an object of match_results class.

• Parameters: This function accepts no parameters.
  Return Value:T his function returns the sequence succeeding the matched sequence in the target string.
  Note: First element always contains the whole regex match while the others contain the particular Capturing Group.
  Below program illustrate the above function: 
  

CPP

// CPP program to illustrate
// match_results suffix() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    string s("Geeksforgeeks is a computer science portal");
    regex re("computer");

    smatch match;

    regex_search(s, match, re);

    cout << "Suffix is: [";
    if (!match.empty()) {
        cout << match.suffix() << "]" << endl;
    }
    return 0;
}

Output:

Suffix is: [ science portal]