demo/lgf_demo.cc File Reference

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lgf_demo.cc File Reference
Demo Programs

## Detailed Description

This program gives an example of how to read and write a digraph and additional maps from/to a stream or a file using the LGF format.

The `"digraph.lgf"` file:

@nodes
label
0
1
2
3
4
5
6
7
@arcs
label capacity
0 1 0 16
0 2 1 12
0 3 2 20
1 2 3 10
1 4 4 10
1 5 5 13
2 3 6 10
2 4 7 8
2 6 8 8
5 3 9 20
3 6 10 25
4 7 11 15
5 7 12 15
6 7 13 18
@attributes
source 0
target 7

And the program which reads it and prints the digraph to the standard output:

/* -*- mode: C++; indent-tabs-mode: nil; -*-
*
* This file is a part of LEMON, a generic C++ optimization library.
*
* Copyright (C) 2003-2009
* Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
* (Egervary Research Group on Combinatorial Optimization, EGRES).
*
* Permission to use, modify and distribute this software is granted
* provided that this copyright notice appears in all copies. For
* precise terms see the accompanying LICENSE file.
*
* This software is provided "AS IS" with no warranty of any kind,
* express or implied, and with no claim as to its suitability for any
* purpose.
*
*/
#include <iostream>
#include <lemon/smart_graph.h>
#include <lemon/lgf_reader.h>
#include <lemon/lgf_writer.h>
using namespace lemon;
int main() {
SmartDigraph g;
SmartDigraph::ArcMap<int> cap(g);
SmartDigraph::Node s, t;
try {
digraphReader(g, "digraph.lgf"). // read the directed graph into g
arcMap("capacity", cap). // read the 'capacity' arc map into cap
node("source", s). // read 'source' node to s
node("target", t). // read 'target' node to t
run();
} catch (Exception& error) { // check if there was any error
std::cerr << "Error: " << error.what() << std::endl;
return -1;
}
std::cout << "A digraph is read from 'digraph.lgf'." << std::endl;
std::cout << "Number of nodes: " << countNodes(g) << std::endl;
std::cout << "Number of arcs: " << countArcs(g) << std::endl;
std::cout << "We can write it to the standard output:" << std::endl;
digraphWriter(g). // write g to the standard output
arcMap("capacity", cap). // write cap into 'capacity'
node("source", s). // write s to 'source'
node("target", t). // write t to 'target'
run();
return 0;
}
`#include <iostream>`
`#include <lemon/smart_graph.h>`
`#include <lemon/lgf_reader.h>`
`#include <lemon/lgf_writer.h>`