.\" ident	@(#)Array_alg:man/reverse.3	3.2
.\"
.\" C++ Standard Components, Release 3.0.
.\"
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.\" Copyright (c) 1988, 1989, 1990 AT&T.  All Rights Reserved.
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.TH \f3reverse\fP \f3Array_alg(3C++)\fP " "
.SH NAME
reverse \- reverse the order of elements in an array
.SH SYNOPSIS OF Array_alg.h
.Bf

    template <class \*(gt>
    void reverse(\*(gt* b,\*(gt* e);
    template <class \*(gt>
    void reverse_c(\*(gt* b1,\*(gt* e1,\*(gt* b2);

.Be
.SH ASSUMPTIONS
.PP
.br
(1) For the copy version, the output array does not
overlap the input array
.br
(2) For the copy version, the output array has
at least as many cells as the input array.
.br
(3) \*(gt has \f4operator=\f1
.SH DESCRIPTION
.PP
These functions reverse the elements of an array.
That is, for every integer \f4i\f1 between \f20\f1
and \f4e\-b\-1\f1, location \f4e\-(i+1)\f1 
will have the same value after reversal 
that \f4b + i\f1 had before reversal.
.sp 0.5v
.IP "\f4template <class \*(gt>\f1"
.IC "\f4void reverse(\*(gt* b,\*(gt* e);\f1"
Reverses the array in place.
.IP "\f4template <class \*(gt>\f1"
.IC "\f4void reverse_c(\*(gt* b1,\*(gt* e1,\*(gt* b2);\f1"
Like \f4reverse\f1 except that the input array
is preserved and the result written to a new array
beginning at location \f4b2\f1.
.SH COMPLEXITY
.PP
If \f2N\f1 is the size of the array,
then complexity is \f2O(N)\f1 for both versions.  
More precisely,
.IP "\f3plain version\f1"
Exactly \f23floor(N/2)\f1 assignments are done.
.IP "\f3copy version\f1"
Exactly \f2N\f1 assignments are done.
.SH NOTES
Because a Block (see \f3Block(3C++)\f1)
can always be used wherever an array is called for,
Array Algorithms can also be used with Blocks.
In fact, these two components were actually designed 
to be used together.
.SH SEE ALSO
.Bf
\f3intro(.)\f1
\f3Block(3C++)\f1
.Be