C++/STL Algorithms Helper/mem fun ref

mem_fun_ref with method from user-defined class

<source lang="cpp">

1. include <algorithm>
2. include <functional>
3. include <iomanip>
4. include <iostream>
5. include <numeric>
6. include <string>
7. include <vector>

using namespace std; class Employee {

  public:
  Employee( string name = "Unknown", int income = 0, int bonus_percentage = 0 );
  int bonus( int games_won ) const;
  void print() const;
  string name() const;
  int income() const;
  private:
  int salary() const;  
  int bonus_percentage_;
  int income_;
  string name_;

}; inline Employee::Employee(string name, int income, int bonus_percentage): bonus_percentage_( bonus_percentage ), income_( income ),name_( name ) {} inline int Employee::bonus( int games_won ) const{

  return static_cast<int>(salary() * ( bonus_percentage_ / 100.0 ) * games_won ); 

} inline void Employee::print() const {

  cout << setw( 10 ) << left << name() << "Income: " << setw( 8 )
     << right << income() << " euro per year   Bonus: "
     << bonus_percentage_ << "% of salary per game won\n";

} inline int Employee::income() const { return income_; } inline string Employee::name() const { return name_; } inline int Employee::salary() const { return static_cast<int>( 0.3 * income() ); } int main( ){

  vector<Employee> myVector;
  myVector.push_back( Employee( "A", 4, 3 ) );
  myVector.push_back( Employee( "B", 1, 3 ) );
  myVector.push_back( Employee( "C", 2, 3 ) );
  myVector.push_back( Employee( "D", 3, 2 ) );
  myVector.push_back( Employee( "E", 5, 1 ) );
  for_each( myVector.begin(), myVector.end(),mem_fun_ref( &Employee::print ) );
  vector<int> temporary( myVector.size() );
  transform( myVector.begin(), myVector.end(),temporary.begin(), mem_fun_ref( &Employee::income ) );
  int average_income = accumulate( temporary.begin(),temporary.end(), 0 ) / temporary.size();
     
  cout << myVector.size()
     << " : "
     << average_income << " \n\n";

}

 </source>

Use mem_fun_ref to pass in a user-defined member function

<source lang="cpp">

1. include <algorithm>
2. include <functional>
3. include <iomanip>
4. include <iostream>
5. include <list>
6. include <string>
7. include <vector>

using namespace std; class PC {

  public:
  enum part { keyboard, mouse, monitor };
  PC( part a_part = PC::keyboard, int id = 0 );
  bool operator<( const PC& rhs ) const;
  void print() const;
  private:
  part part_;
  int id_;

}; inline PC::PC( part a_part, int id ) : part_( a_part ), id_( id ){} inline bool PC::operator<( const PC& rhs ) const{

  return id_ < rhs.id_; 

} void PC::print() const {

  string component;
  if( part_ == keyboard )
     component = "keyboard";
  else if( part_ == mouse )
     component = "mouse";
  else
     component = "monitor";
  cout << "ID: " << setw( 8 ) << left << id_ << " PC: " << component << endl;

} int main( ) {

  list<PC> listA;
  listA.push_back( PC( PC::keyboard, 3 ) );
  listA.push_back( PC( PC::mouse, 1 ) );
  listA.push_back( PC( PC::monitor, 9 ) );
  listA.push_back( PC( PC::keyboard, 2 ) );
  listA.push_back( PC( PC::monitor, 8 ) );
  for_each( listA.begin(), listA.end(),mem_fun_ref( &PC::print ) );

}

 </source>