$line = "one two three four four SIX";

$line =~ s/two/six/;

$line =~ s/four/ten/g;

$line =~ s/th(re)e/whe$1/

if ($line =~ /six/i) {

}

##</code><code>##

//================================================
// C++11 Perl equivalency wrapper functions
//================================================
#include <string>
#include <regex>
#include <iostream>
#include <vector>

using namespace std;

// Equivalent to Perl: $s =~ s/$e1/$e2/g;
inline void StrReplaceXg(string& s, string e1, string e2) {
  string r = regex_replace(s, regex{e1}, e2);
  s = r;
}

// Equivalent to Perl: $s =~ s/$e1/$e2/;
inline void StrReplaceX(string& s, string e1, string e2) {
  string r = regex_replace(s, regex{e1}, e2,
                regex_constants::format_first_only);
  s = r;
}

// Equivalent to Perl: if ($s =~ /$e1/) { /*dosomething with m[0]...*/ }
inline bool StrMatchX(string& s, string e1, vector<string>& m) {
   smatch  M;
   m.clear();
   bool rc = regex_match(s, M, regex{e1});
   if (rc) {
       for(int i=1; i < (int) M.size(); i++) {
          m.push_back(M[i].str());
       }
   }
   return rc;
}


//================================================
// Example 1: C++11 vs Perl
//================================================

// PERL:
//sub example1() {
//     $s = "one two three four four";
//     $s =~ s/two/stuff/;
//     print "s:$s\n";
//}

// C++11:
void example1() {
      string s = string{"one two three four four"};
      StrReplaceX  (s, R"(two)", "stuff");
      cout << "s:" << s << "\n";
}

//================================================
// Example 2: C++11 vs Perl
//================================================

//  PERL:
//sub example2() {
//     $s = "one two three four four";
//     $s =~ s/four/stuff/g;
//     print "s:$s\n";
//}

//  C++11:
void example2() {
     string s = string{"one two three four four"};
     StrReplaceXg (s, R"(four)", "stuff");
     cout << "s:" << s << "\n";
}

//================================================
// Example 3: C++11 vs Perl
//================================================

//  PERL:
//sub example3() {
//  $s = "one two three four four";
//  if ($s =~ /(\S+) (\S+)/) {
//    print "match1: $1\n";
//    print "match2: $2\n";
//  }
//}

//  C++11:
void example3() {
  string s = string{"one two three four four"};
  vector<string> m;
  if (StrMatchX(s, R"((\S+) (\S+))", m)) {
    cout << "match1:" << m[0] << "\n";
    cout << "match2:" << m[1] << "\n";
  }
}


int main(int, char**) {
  example1();
  example2();
  example3();
  return 0;
}