Microsoft KB Archive/157561

= STL Sample for the Predicate Version of the merge Function =

Article ID: 157561

Article Last Modified on 12/2/2003

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APPLIES TO

 The Standard C++ Library, when used with:  Microsoft Visual C++ 4.2 Professional Edition

 Microsoft Visual C++ 4.2 Enterprise Edition

 Microsoft Visual C++ 5.0 Learning Edition 

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This article was previously published under Q157561

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SUMMARY
The sample code below illustrates how to use the predicate version of the merge STL function in Visual C++.

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Prototype
template<class InputIterator1, class InputIterator2, class OutputIterator class Compare> inline

OutputIterator merge( InputIterator1 first1,                        InputIterator1 last1,                         InputIterator2 first2,                         InputIterator2 last2                         OutputIterator result,                         Compare compare ) NOTE: The class/parameter names in the prototype do not match the original version in the header file. They have been modified to improve readability.

Description
The merge algorithm merges two sorted sequences: [first1..last1) and [first2..last2) into a single sorted sequence starting at result.

This version assumes that the ranges [first1..last1) and [first2..last2) are sorted using compare function. If both ranges contain equal values, the value from the first range will be stored first.

The result of merging overlapping ranges is undefined.

Sample Code
////////////////////////////////////////////////////////////////////// // // Compile options needed: /GX // // merge.cpp : Illustrates how to use predicate version of the merge //            function. // // Functions: // //   merge : Merge two sorted sequences //           into a single sorted list. // // 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
 * 1) pragma warning(disable: 4786)

using namespace std;
 * 1) include
 * 2) include
 * 3) include
 * 4) include
 * 5) include

void main {   const int MAX_ELEMENTS = 8 ;

// Define a template class vector of int typedef vector<int, allocator > IntVector ;

//Define an iterator for template class vector of ints typedef IntVector::iterator IntVectorIt ;

IntVector NumbersVector(MAX_ELEMENTS) ;

IntVectorIt startv, endv, itv ;

// Define a template class list of int typedef list<int, allocator > IntList ;

//Define an iterator for template class list of ints typedef IntList::iterator IntListIt ;

IntList NumbersList ;

IntListIt first, last, itl ;

// Define a template class deque of int typedef deque<int, allocator > IntDeque ;

//Define an iterator for template class deque of ints typedef IntDeque::iterator IntDequeIt ;

IntDeque NumbersDeque(2 * MAX_ELEMENTS) ;

IntDequeIt itd ;

// Initialize vector NumbersVector NumbersVector[0] = 4 ; NumbersVector[1] = 10; NumbersVector[2] = 70 ; NumbersVector[3] = 10 ; NumbersVector[4] = 30 ; NumbersVector[5] = 69 ; NumbersVector[6] = 96 ; NumbersVector[7] = 100;

startv = NumbersVector.begin ;  // location of first // element of NumbersVector

endv = NumbersVector.end ; // one past the location // last element of NumbersVector

// sort NumbersVector, merge requires the sequences // to be sorted sort(startv, endv, less ) ;

// print content of NumbersVector cout << "NumbersVector { " ; for(itv = startv; itv != endv; itv++) cout << *itv << " " ; cout << " }\n" << endl ;

// Initialize vector NumbersList for(int i = 0; i < MAX_ELEMENTS; i++) NumbersList.push_back(i) ;

first = NumbersList.begin ;  // location of first // element of NumbersList

last = NumbersList.end ; // one past the location // last element of NumbersList

// print content of NumbersList cout << "NumbersList { " ; for(itl = first; itl != last; itl++) cout << *itl << " " ; cout << " }\n" << endl ;

// merge the elements of NumbersVector // and NumbersList and place the // results in NumbersDeque merge(startv, endv, first, last, NumbersDeque.begin, less ) ;

cout << "After calling merge\n" << endl ;

// print content of NumbersDeque cout << "NumbersDeque { " ; for(itd = NumbersDeque.begin;       itd != NumbersDeque.end; itd++) cout << *itd << " " ; cout << " }\n" << endl ; } Program Output is:

NumbersVector { 4 10 10 30 69 70 96 100 }

NumbersList { 0 1 2 3 4 5 6 7 }

After calling merge

NumbersDeque { 0 1 2 3 4 4 5 6 7 10 10 30 69 70 96 100 }

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