.\" ident	@(#)Array_alg:man/unique.3	3.2
.\"
.\" C++ Standard Components, Release 3.0.
.\"
.\" Copyright (c) 1991, 1992 AT&T and UNIX System Laboratories, Inc.
.\" Copyright (c) 1988, 1989, 1990 AT&T.  All Rights Reserved.
.\"
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.TH \f3unique\fP \f3Array_alg(3C++)\fP " "
.SH NAME
unique \- remove repeated elements from a sorted array
.SH SYNOPSIS OF Array_alg.h
.Bf

    template <class \*(gt>
    \*(gt* unique(\*(gt* b,\*(gt* e);
    template <class \*(gt>
    \*(gt* unique_c(\*(gt* b1,\*(gt* e1,\*(gt* b2);
    template <class \*(gt>
    \*(gt* unique_r(int (*rel)(const \*(gt*,const \*(gt*),
		    \*(gt* b,\*(gt* e);
    template <class \*(gt>
    \*(gt* unique_rc(int (*rel)(const \*(gt*,const \*(gt*),
		     \*(gt* b1,\*(gt* e1,\*(gt* b2);

.Be
.SH ASSUMPTIONS
.PP
(1) For the non-relational versions, \*(gt\f4::operator==\f1
defines an equivalence relation on \*(gt
.br
(2) For the relational versions, \f4rel\f1
defines an equivalence relation on \*(gt
.br
(3) For the copy versions, the output array does not
overlap the input array
.br
(4) For the copy versions, the output array has enough
cells to hold the result
.br
(5) \*(gt has \f4operator=\f1
.SH DESCRIPTION
.PP
These functions remove all but the first element from 
every consecutive group of equal elements in an array.
They return a pointer to the location after the 
last unique element.
.sp 0.5v
.IP "\f4template <class \*(gt>\f1"
.IC "\f4\*(gt* unique(\*(gt* b,\*(gt* e);\f1"
Uses \f4\*(gt::operator==\f1 to define equality.
.IP "\f4template <class \*(gt>\f1"
.IC "\f4\*(gt* unique_c(\*(gt* b1,\*(gt* e1,\*(gt* b2);\f1"
Like \f4unique\f1 except that the input array is preserved
and the result written to a new array beginning at 
location \f4b2\f1.
.IP "\f4template <class \*(gt>\f1"
.IC "\f4\*(gt* unique_r(int (*rel)(const \*(gt*,const \*(gt*),\*(gt* b,\*(gt* e);\f1"
Uses \f4rel\f1 to define equality.
.IP "\f4template <class \*(gt>\f1"
.IC "\f4\*(gt* unique_rc(int (*rel)(const \*(gt*,const \*(gt*),\*(gt* b1,\*(gt* e1,\*(gt* b2);\f1"
Like \f4unique_r\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 all versions.
Exactly \f2N\-1\f1 equality tests and at most \f2N\-2\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
\f3rem_dup(.)\f1
\f3Block(3C++)\f1
.Be