Article: Q157156
Product(s): Microsoft C Compiler
Version(s): winnt:
Operating System(s):
Keyword(s): _IK
Last Modified: 05-MAY-2001
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The information in this article applies to:
- The Standard C++ Library, included with:
- *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, version 4.2
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SUMMARY
=======
The sample code below illustrates how to use the predicate versions of the
make_heap, sort_heap, push_heap, pop_heap, begin, and end STL functions in
Visual C++.
MORE INFORMATION
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Required Header
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<algorithm>
Prototype
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template<class RandomAccessIterator, class Compare> inline
void make_heap(RandomAccessIterator first,
RandomAccessIterator last,
Compare compare)
template<class RandomAccessIterator, class Compare> inline
void sort_heap(RandomAccessIterator first,
RandomAccessIterator last,
Compare compare)
template<class RandomAccessIterator, class Compare> inline
void push_heap(RandomAccessIterator first,
RandomAccessIterator last,
Compare compare)
template<class RandomAccessIterator, class Compare> inline
void pop_heap(RandomAccessIterator first,
RandomAccessIterator last,
Compare compare)
NOTE: The class/parameter names in the prototype do not match the original
version in the header file. Some have been modified to improve readability.
Description
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A heap is a sequence of elements organized like a binary tree. Each heap element
corresponds to a tree node. The first value in the sequence [first..last) is the
root, and is ordered by the predicate. For example, if the predicate is
greater<int>, every element in the heap satisfies the following; every
element is greater than or equal to its parent. The smallest element is stored
in the root, and all children hold progressively larger values.
The make_heap function converts the range [first..last) into a heap.
The sort_heap function sorts a "heapified" sequence that was created using the
make_heap function.
The push_heap function inserts a new value into the heap.
The pop_heap function swaps the first and last elements in the heap specified by
[first, last), then reduces the length of the sequence by one before restoring
the heap property.
The predicate versions of the heap functions use the compare function for
comparisons.
Sample Code
-----------
//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// heap_functions.cpp : Illustrates how to use the predicate versions
// of the make_heap, sort_heap, push_heap
// and pop_heap functions.
//
// Functions:
//
// make_heap : Convert a sequence to a heap.
// sort_heap : Sort a heap.
// push_heap : Insert an element in a heap.
// pop_heap : Remove the top element from a heap.
//
// Written by Kalindi Sanghrajka
// of Microsoft Product Support Services,
// Software Core Developer Support.
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////
// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)
#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
using namespace std;
void main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of int
typedef vector<int, allocator<int> > IntVector ;
//Define an iterator for template class vector of strings
typedef IntVector::iterator IntVectorIt ;
IntVector Numbers(VECTOR_SIZE) ;
IntVectorIt it ;
// Initialize vector Numbers
Numbers[0] = 4 ;
Numbers[1] = 10;
Numbers[2] = 70 ;
Numbers[3] = 10 ;
Numbers[4] = 30 ;
Numbers[5] = 69 ;
Numbers[6] = 96 ;
Numbers[7] = 100;
// print content of Numbers
cout << "Numbers { " ;
for(it = Numbers.begin(); it != Numbers.end(); it++)
cout << *it << " " ;
cout << " }\n" << endl ;
// convert Numbers into a heap
make_heap(Numbers.begin(), Numbers.end(), greater<int>()) ;
cout << "After calling make_heap\n" << endl ;
// print content of Numbers
cout << "Numbers { " ;
for(it = Numbers.begin(); it != Numbers.end(); it++)
cout << *it << " " ;
cout << " }\n" << endl ;
// sort the heapified sequence Numbers
sort_heap(Numbers.begin(), Numbers.end(), greater<int>()) ;
cout << "After calling sort_heap\n" << endl ;
// print content of Numbers
cout << "Numbers { " ;
for(it = Numbers.begin(); it != Numbers.end(); it++)
cout << *it << " " ;
cout << " }\n" << endl ;
make_heap(Numbers.begin(), Numbers.end(), greater<int>()) ;
//insert an element in the heap
Numbers.push_back(7) ;
push_heap(Numbers.begin(), Numbers.end(), greater<int>()) ;
cout << "After calling push_heap()\n" << endl;
// print content of Numbers
cout << "Numbers { " ;
for(it = Numbers.begin(); it != Numbers.end(); it++)
cout << *it << " " ;
cout << " }\n" << endl ;
//remove the root element from the heap Numbers
pop_heap(Numbers.begin(), Numbers.end(), greater<int>()) ;
cout << "After calling pop_heap\n" << endl ;
// print content of Numbers
cout << "Numbers { " ;
for(it = Numbers.begin(); it != Numbers.end(); it++)
cout << *it << " " ;
cout << " }\n" << endl ;
}
Program Output is:
Numbers { 4 10 70 10 30 69 96 100 }
After calling make_heap
Numbers { 4 10 69 10 30 70 96 100 }
After calling sort_heap
Numbers { 100 96 70 69 30 10 10 4 }
After calling push_heap()
Numbers { 4 7 10 30 100 10 70 96 69 }
After calling pop_heap
Numbers { 7 30 10 69 100 10 70 96 4 }
REFERENCES
==========
Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.
Additional query words: STL make_heap sort_heap push_heap pop_heap begin end
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Keywords : _IK
Technology : kbVCsearch kbAudDeveloper kbVCLibrary
Version : winnt:
Issue type : kbhowto
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