1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
3 * This file is a part of LEMON, a generic C++ optimization library.
5 * Copyright (C) 2003-2008
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
21 \page hello_lemon Compile Your First Code
23 First of all you have to install LEMON on your system (see
24 \ref install for instructions).
25 After that you can paste the following code segment into a file
26 <tt>hello_lemon.cc</tt> to have a first working program that uses LEMON.
28 \dontinclude hello_lemon.cc
32 First let us briefly explain how this example program works.
33 (The used notions will be discussed in detail in the following sections.)
35 After some convenience typedefs we create a directed graph (\e digraph)
36 and add some nodes and arcs to it.
37 ListDigraph is one of the digraph classes implemented in LEMON.
38 It is based on linked lists, therefore iterating through its nodes and
41 Then we iterate through all nodes of the digraph and print their unique
42 IDs. We use a constructor of the node iterator to initialize it to the
44 The <tt>operator++</tt> is used to step to the next node. After the last
45 node the iterator becomes invalid (i.e. it is set to \c INVALID).
46 This is what we exploit in the stop condition.
47 We iterate through all arcs of the digraph very similarly and print the
48 IDs of their source (tail) and target (head) nodes using the \c source()
49 and \c target() member functions.
51 After that we create an arc map, which is actually a mapping that assigns
52 an \c int value (length) to each arc, and we set this value for each arc.
53 Finally we iterate through all arcs again and print their lengths.
55 Now let us compile this simple example program.
57 \section hello_lemon_system If LEMON is Installed System-Wide
59 If LEMON is installed system-wide (into directory \c /usr/local),
60 then it is very easy to compile this program with the
61 following command (the argument <tt>-lemon</tt> tells the compiler
62 that we are using the installed LEMON):
65 g++ -lemon hello_lemon.cc -o hello_lemon
68 As a result you will get the exacutable \c hello_lemon in the current
69 directory, which you can run by the following command.
75 \section hello_lemon_user If LEMON is Installed User-Local
77 Compiling the code is a bit more difficult if you installed LEMON
78 user-local into a directory (e.g. <tt>~/lemon</tt>) or if you just
79 skipped the step <tt>make install</tt>.
80 You have to issue a command like this.
83 g++ -lemon -I ~/lemon -L ~/lemon/lemon/.libs hello_lemon.cc -o hello_lemon
86 If everything has gone well, then our program prints out the followings.
90 This is LEMON library here. We have a direceted graph.
93 Arcs: (2,3) (1,3) (1,2) (0,2) (0,1)
95 There is a map on the arcs (length):
104 You may note that iterating through the nodes and arcs is done in the
105 reverse order compared to the creating order (the IDs are in decreasing
107 This is due to implementation aspects, that may differ at other graph
108 types, moreover it may be changed in the next releases.
109 Thus you should not exploit this method in any way, you should not
110 suppose anything about the iteration order.
112 If you managed to compile and run this example code without any problems,
113 you can go on reading this tutorial to get to know more features and tools
115 Otherwise if you encountered problems that you did not manage to solve,
117 <a href="mailto:lemon-user@lemon.cs.elte.hu"><b>contact us</b></a>.