How to use the set::swap, set::begin and set::end Standard Template Library (STL) functions in Visual C++ (158580)

MORE INFORMATION

Required header

   <set>

Prototype

   template<class _K, class _Pr, class _A>
   class set {
   public:
   // Function 1:

      void swap(_Myt& _X);
   // Function 2:
      friend void swap(_Myt& _X, _Myt& _Y);
   // Function 3:
      const_iterator begin() const;
   // Function 4:
      const_iterator end() const;
   }

Note The class/parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.

Description

The swap function swaps the two controlled sequences. The begin function returns a bidirectional iterator that points at the first element of the sequence. The end function returns a bidirectional iterator that points just beyond the end of the sequence.

Sample code

////////////////////////////////////////////////////////////////////// 
// 
// Compile options needed: -GX
// 
// SetSwapBeginEnd.cpp:
//      Illustrates how to use the swap function to exchange the two
//      controlled sequences. It also illustrates how to use the
//      begin function to get a bidirectional iterator that points at
//      the first element of the controlled sequence. Finally, it
//      illustrates how to use the end function to get a bidirectional
//      iterator that points just beyond the end of the controlled
//      sequence.
// 
// Functions:
// 
//    swap        Exchanges the two controlled sequences.
//    begin       Returns a bidirectional iterator that points at the
//                first element of the controlled sequence.
//    end         Returns a bidirectional iterator that points just
//                beyond the end of the controlled sequence.
// 
// Written by Derek Jamison
// of Microsoft Technical Support,
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
////////////////////////////////////////////////////////////////////// 

#pragma warning(disable:4786)

#include <set>
#include <iostream>

#if _MSC_VER > 1020   // if VC++ version is > 4.2
   using namespace std;  // std c++ libs implemented in std
   #endif

typedef set<int,less<int>,allocator<int> > SET_INT;

void main() {

  SET_INT s1;
  SET_INT s2;
  SET_INT::iterator i;
  cout << "s1.insert(5)" << endl;
  s1.insert(5);
  cout << "s1.insert(10)" << endl;
  s1.insert(10);
  cout << "s1.insert(15)" << endl;
  s1.insert(15);
  cout << "s2.insert(2)" << endl;
  s2.insert(2);
  cout << "s2.insert(4)" << endl;
  s2.insert(4);

  cout << "swap(s1,s2)" << endl;
  swap(s1,s2);

  // Displays: 2,4

  for (i=s1.begin();i!=s1.end();i++)

     cout << "s1 has " << *i << " in its set." << endl;

  // Displays: 5,10,15

  for (i=s2.begin();i!=s2.end();i++)

     cout << "s2 has " << *i << " in its set." << endl;

  cout << "s1.swap(s2)" << endl;
  s1.swap(s2);

  // Displays: 5,10,15

  for (i=s1.begin();i!=s1.end();i++)

     cout << "s1 has " << *i << " in its set." << endl;

  // Displays: 2,4

  for (i=s2.begin();i!=s2.end();i++)

     cout << "s2 has " << *i << " in its set." << endl;

}

Program output

s1.insert(5)
s1.insert(10)
s1.insert(15)
s2.insert(2)
s2.insert(4)
swap(s1,s2)
s1 has 2 in its set.
s1 has 4 in its set.
s2 has 5 in its set.
s2 has 10 in its set.
s2 has 15 in its set.
s1.swap(s2)
s1 has 5 in its set.
s1 has 10 in its set.
s1 has 15 in its set.
s2 has 2 in its set.
s2 has 4 in its set.