INFO: (swap, begin, end) Function

ID: Q158580

The information in this article applies to:

The Standard C++ Library, used with:
- Microsoft Visual C++, 32-bit Editions, versions 4.2, 5.0, 6.0

SUMMARY

The following sample code illustrates how to use the set::swap, set::begin and set::end STL functions in Visual C++.

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.

REFERENCES

Visual C++ Books Online: Visual C++ Books; C/C++; Standard C++ Library Reference

Additional query words: STL STLSample swap begin end

Keywords : kbcode kbVC420 kbVC500 kbVC600 kbDSupport STLIss
Version : winnt:4.2,5.0,6.0
Platform : winnt
Issue type : kbinfo