Using your own sorting functor - C++ STL

C++ examples for STL:map

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Description

Using your own sorting functor

Demo Code

#include <iostream>
#include <map>
#include <string>

using namespace std;

class FullName {/*w  w  w  .  j ava 2s .  c o  m*/
   friend class FullNameLessThan;
public:

   FullName(const string& first, const string& last) : lastName_(last), firstName_(first) {}

   string getFirstName() const {return(firstName_);}
   string getLastName() const {return(lastName_);}
private:
   string lastName_;
   string firstName_;
};

class FullNameLessThan {
public:
   bool operator()(const FullName& per1, const FullName& per2) const {
      if (per1.lastName_ < per2.lastName_)
         return(true);
      else if (per1.lastName_ == per2.lastName_)
         return(per1.firstName_ < per2.firstName_);
      else
         return(false);
   }
};

int main() {

   map<FullName, string, FullNameLessThan> personMap;

   FullName per1("B", "S"),
      per2("J", "G"),
      per3("F", "S"),
      per4("A", "G");

   personMap[per1] = "cool";
   personMap[per2] = "not cool";
   personMap[per3] = "not cool";
   personMap[per4] = "cool";

   for (map<FullName, string, FullNameLessThan>::const_iterator p = personMap.begin(); p != personMap.end(); ++p) {
      cout << p->first.getFirstName() << " " << p->first.getLastName() << " is " << p->second << endl;
   }
}

Result


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