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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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*
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* This file is a part of LEMON, a generic C++ optimization library.
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*
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* Copyright (C) 2003-2008
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* Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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* (Egervary Research Group on Combinatorial Optimization, EGRES).
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*
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* Permission to use, modify and distribute this software is granted
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* provided that this copyright notice appears in all copies. For
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* precise terms see the accompanying LICENSE file.
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*
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* This software is provided "AS IS" with no warranty of any kind,
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* express or implied, and with no claim as to its suitability for any
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* purpose.
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*
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*/
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namespace lemon {
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/**
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[PAGE]hello_lemon[PAGE] Compile Your First Code
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First of all you have to install LEMON on your system (see
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\ref install for instructions).
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After that you can paste the following code segment into a file
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<tt>hello_lemon.cc</tt> to have a first working program that uses LEMON.
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\dontinclude hello_lemon.cc
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\skip #include
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\until }
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First let us briefly explain how this example program works.
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(The used notions will be discussed in detail in the following sections.)
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After some convenience typedefs we create a directed graph (\e digraph)
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and add some nodes and arcs to it.
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ListDigraph is one of the digraph classes implemented in LEMON.
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It is based on linked lists, therefore iterating through its nodes and
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arcs is fast.
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Then we iterate through all nodes of the digraph and print their unique
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IDs. We use a constructor of the node iterator to initialize it to the
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first node.
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The <tt>operator++</tt> is used to step to the next node. After the last
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node the iterator becomes invalid (i.e. it is set to \c INVALID).
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This is what we exploit in the stop condition.
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We iterate through all arcs of the digraph very similarly and print the
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IDs of their source (tail) and target (head) nodes using the \c source()
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and \c target() member functions.
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After that we create an arc map, which is actually a mapping that assigns
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an \c int value (length) to each arc, and we set this value for each arc.
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Finally we iterate through all arcs again and print their lengths.
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Now let us compile this simple example program.
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[SEC]hello_lemon_system[SEC] If LEMON is Installed System-Wide
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If LEMON is installed system-wide (into directory \c /usr/local),
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then it is very easy to compile this program with the
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following command (the argument <tt>-lemon</tt> tells the compiler
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that we are using the installed LEMON):
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\verbatim
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g++ -lemon hello_lemon.cc -o hello_lemon
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\endverbatim
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As a result you will get the exacutable \c hello_lemon in the current
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directory, which you can run by the following command.
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\verbatim
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./hello_lemon
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\endverbatim
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[SEC]hello_lemon_user[SEC] If LEMON is Installed User-Local
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Compiling the code is a bit more difficult if you installed LEMON
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user-local into a directory (e.g. <tt>~/lemon</tt>) or if you just
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skipped the step <tt>make install</tt>.
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You have to issue a command like this.
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\verbatim
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g++ -lemon -I ~/lemon -L ~/lemon/lemon/.libs hello_lemon.cc -o hello_lemon
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\endverbatim
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If everything has gone well, then our program prints out the followings.
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\verbatim
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Hello World!
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This is LEMON library here. We have a direceted graph.
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Nodes: 3 2 1 0
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Arcs: (2,3) (1,3) (1,2) (0,2) (0,1)
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There is a map on the arcs (length):
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length(2,3)=10
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length(1,3)=25
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length(1,2)=5
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length(0,2)=20
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length(0,1)=10
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\endverbatim
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You may note that iterating through the nodes and arcs is done in the
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reverse order compared to the creating order (the IDs are in decreasing
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order).
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This is due to implementation aspects, that may differ at other graph
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types, moreover it may be changed in the next releases.
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Thus you should not exploit this method in any way, you should not
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suppose anything about the iteration order.
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If you managed to compile and run this example code without any problems,
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you can go on reading this tutorial to get to know more features and tools
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of LEMON.
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Otherwise if you encountered problems that you did not manage to solve,
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do not hesitate to
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<a href="mailto:lemon-user@lemon.cs.elte.hu"><b>contact us</b></a>.
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[TRAILER]
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*/
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}
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