1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="AUTHOR" CONTENT="pme@sources.redhat.com (Phil Edwards)">
<META NAME="KEYWORDS" CONTENT="HOWTO, libstdc++, GCC, g++, libg++, STL">
<META NAME="DESCRIPTION" CONTENT="HOWTO for the libstdc++ chapter 25.">
<META NAME="GENERATOR" CONTENT="vi and eight fingers">
<TITLE>libstdc++-v3 HOWTO: Chapter 25</TITLE>
<LINK REL=StyleSheet HREF="../lib3styles.css">
<!-- $Id: howto.html,v 1.5 2000/12/03 23:47:48 jsm28 Exp $ -->
</HEAD>
<BODY>
<H1 CLASS="centered"><A NAME="top">Chapter 25: Algorithms</A></H1>
<P>Chapter 25 deals with the generalized subroutines for automatically
transforming lemmings into gold.
</P>
<!-- ####################################################### -->
<HR>
<H1>Contents</H1>
<UL>
<LI><A HREF="#1">Prerequisites</A>
<LI><A HREF="#2">Topic</A>
</UL>
<HR>
<!-- ####################################################### -->
<H2><A NAME="1">Prerequisites</A></H2>
<P>The neatest accomplishment of the algorithms chapter is that all the
work is done via iterators, not containers directly. This means two
important things:
<OL>
<LI>Anything that behaves like an iterator can be used in one of
these algorithms. Raw pointers make great candidates, thus
built-in arrays are fine containers. So do your own iterators.
<LI>The algorithms do not (and cannot) affect the container as a
whole; only the things between the two iterator endpoints. If
you pass a range of iterators only enclosing the middle third of
a container, then anything outside that range is inviolate.
</OL>
</P>
<P>Even strings can be fed through the algorithms here, although the
string class has specialized versions of many of these functions (for
example, <TT>string::find()</TT>). Most of the examples on this
page will use simple arrays of integers as a playground for
algorithms, just to keep things simple.
<A NAME="Nsize">The use of <B>N</B></A> as a size in the examples is
to keep things easy to read but probably won't be legal code. You can
use wrappers such as those described in the
<A HREF="../23_containers/howto.html">containers chapter</A> to keep
real code readable.
</P>
<P>The single thing that trips people up the most is the definition of
<EM>range</EM> used with iterators; the famous
"past-the-end" rule that everybody loves to hate. The
<A HREF="../24_iterators/howto.html">iterators chapter</A> of this
document has a complete explanation of this simple rule that seems to
cause so much confusion. Once you get <EM>range</EM> into your head
(it's not that hard, honest!), then the algorithms are a cakewalk.
</P>
<P>
</P>
<P>Return <A HREF="#top">to top of page</A> or
<A HREF="../faq/index.html">to the FAQ</A>.
</P>
<HR>
<H2><A NAME="2">Topic</A></H2>
<P>Blah.
</P>
<P>Return <A HREF="#top">to top of page</A> or
<A HREF="../faq/index.html">to the FAQ</A>.
</P>
<!-- ####################################################### -->
<HR>
<P CLASS="fineprint"><EM>
Comments and suggestions are welcome, and may be sent to
<A HREF="mailto:pme@sources.redhat.com">Phil Edwards</A> or
<A HREF="mailto:gdr@gcc.gnu.org">Gabriel Dos Reis</A>.
<BR> $Id: howto.html,v 1.5 2000/12/03 23:47:48 jsm28 Exp $
</EM></P>
</BODY>
</HTML>
|
