.\" ident @(#)reverse.3
.\" Standard Template Library
.\" $$RW_INSERT_HEADER "slyrs.man"
.TH reverse 3C++ "02 Apr 1998" "Rogue Wave Software" "-"
.ce2
Standard C++ Library   
Copyright 1998, Rogue Wave Software, Inc.   

.SH NAME

\f2reverse\fP

\ - Reverses the order of elements in a collection.



.SH  SYNOPSIS


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#include <algorithm>
.br
template <class BidirectionalIterator>
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void reverse (BidirectionalIterator first,
.RE
.RS 13
BidirectionalIterator last);



.SH  DESCRIPTION


The algorithm reverse reverses the elements in a sequence so that the last element becomes the new first element, and the first element becomes the new last. For each non-negative integer \f2i <= (last - first)/2\fP, reverse applies swap to all pairs of iterators \f2first + I, (last - I) - 1\fP. 

Because the iterators are assumed to be bidirectional, reverse does not return anything.



.SH  COMPLEXITY


reverse performs exactly \f2(last - first)/2\fP swaps.



.SH  EXAMPLE



.RE
.RS 0
//
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// reverse.cpp
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//
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#include <algorithm>
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#include <vector>
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#include <iostream>
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using namespace std;
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int main()
.RE
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{
.RE
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//Initialize a vector with an array of ints
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int arr[10] = {1,2,3,4,5,6,7,8,9,10};
.br
vector<int> v(arr, arr+10);
.RE
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.RE
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//Print out elements in original (sorted) order
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cout << "Elements before reverse: " << endl << "     ";
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copy(v.begin(),v.end(),
.RE
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ostream_iterator<int,char>(cout," "));
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cout << endl << endl;
.RE
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.RE
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//Reverse the ordering
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reverse(v.begin(), v.end());
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.RE
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//Print out the reversed elements
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cout << "Elements after reverse: " << endl << "     ";
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.RE
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copy(v.begin(),v.end(),
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ostream_iterator<int,char>(cout," "));
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cout << endl;
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return 0;
.RE
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}

.br
.RE
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Program Output



.RE
.RS 0

.br
Elements before reverse:
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1 2 3 4 5 6 7 8 9 10
.RE
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Elements after reverse:
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10 9 8 7 6 5 4 3 2 1
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A reverse_copy to cout:
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1 2 3 4 5 6 7 8 9 10



.SH  WARNINGS


If your compiler does not support default template parameters, then you always need to supply the \f2Allocator\fP template argument. For instance, you need to write:

\f2vector<int, allocator<int> >\fP

instead of:

\f2vector<int>\fP

If your compiler does not support namespaces, then you do not need the using declaration for \f2std\fP.



.SH  SEE ALSO


reverse_copy, swap