Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.

NAME

 
inplace_merge
 
 - Merges two sorted sequences into one.
 
 
 

SYNOPSIS

 
 
#include <algorithm>
template <class BidirectionalIterator>

void inplace_merge(BidirectionalIterator first,

BidirectionalIterator middle,
BidirectionalIterator last);

 
template <class BidirectionalIterator, class Compare>

void inplace_merge(BidirectionalIterator first,

BidirectionalIterator middle,
BidirectionalIterator last,
Compare comp);
 
 
 

DESCRIPTION

 
 
The inplace_merge algorithm merges two sorted consecutive ranges [first, middle) and [middle, last), and puts the result of the merge into the range [first, last). The merge is stable, which means that if the two ranges contain equivalent elements, the elements from the first range always precede the elements from the second. 
 
There are two versions of the inplace_merge algorithm. The first version uses the less than operator (operator<) as the default for comparison, and the second version accepts a third argument that specifies a comparison operator. 
 
 
 

COMPLEXITY

 
 
When enough additional memory is available, inplace_merge does at most (last - first) - 1 comparisons. If no additional memory is available, an algorithm with O(NlogN) complexity (where N is equal to last-first) may be used. 
 
 
 

EXAMPLE

//
// merge.cpp
//

#include <algorithm>
#include <vector>
#include <functional>
#include <iostream>

using namespace std;
 
int main()

{

int d1[4] = {1,2,3,4};
int d2[8] = {11,13,15,17,12,14,16,18};

// Set up two vectors

vector<int> v1(d1,d1 + 4), v2(d1,d1 + 4);

// Set up four destination vectors

vector<int> v3(d2,d2 + 8),v4(d2,d2 + 8),

v5(d2,d2 + 8),v6(d2,d2 + 8);

// Set up one empty vector

vector<int> v7;

// Merge v1 with v2

merge(v1.begin(),v1.end(),v2.begin(),v2.end(),

v3.begin());

// Now use comparator

merge(v1.begin(),v1.end(),v2.begin(),v2.end(),v4.begin(),

less<int>());

// In place merge v5

vector<int>::iterator mid = v5.begin();
advance(mid,4);

inplace_merge(v5.begin(),mid,v5.end());
// Now use a comparator on v6

mid = v6.begin();
advance(mid,4);

inplace_merge(v6.begin(),mid,v6.end(),less<int>());
// Merge v1 and v2 to empty vector using insert iterator

merge(v1.begin(),v1.end(),v2.begin(),v2.end(),

back_inserter(v7));

// Copy all cout

ostream_iterator<int,char> out(cout," ");
copy(v1.begin(),v1.end(),out);
cout << endl;
copy(v2.begin(),v2.end(),out);
cout << endl;
copy(v3.begin(),v3.end(),out);
cout << endl;
copy(v4.begin(),v4.end(),out);
cout << endl;
copy(v5.begin(),v5.end(),out);
cout << endl;
copy(v6.begin(),v6.end(),out);
cout << endl;
copy(v7.begin(),v7.end(),out);
cout << endl;

// Merge v1 and v2 to cout

merge(v1.begin(),v1.end(),v2.begin(),v2.end(),

ostream_iterator<int,char>(cout," "));

cout << endl;
return 0;

}

Program Output
 
 
 
 
1 2 3 4
1 2 3 4
1 1 2 2 3 3 4 4
1 1 2 2 3 3 4 4
11 12 13 14 15 16 17 18
11 12 13 14 15 16 17 18
1 1 2 2 3 3 4 4
1 1 2 2 3 3 4 4
 
 
 

WARNINGS

 
 
If your compiler does not support default template parameters, then you always need to supply the Allocator template argument. For instance, you have to write:
 
vector<int, allocator,int> >
 
instead of:
 
vector<int>
 
If your compiler does not support namespaces, then you do not need the using declaration for std. 
 
 
 

SEE ALSO

 
 
merge
 

Rogue Wave Software  —  Last change: 02 Apr 1998