Question

我正在尝试使用Boost Graph Library创建一个名为GraphService的类。它应该计算图形上的各种内容，并将属性（如节点度分布）返回到其他类。这是我的图形头文件的一部分，称为Graph.h：

typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS,
                          vertex_info, edge_info, graph_info, boost::listS> Graph;
typedef boost::graph_traits<Graph>::vertex_descriptor VertexDescriptor;
typedef boost::graph_traits<Graph>::edge_descriptor EdgeDescriptor;
typedef boost::graph_traits<Graph>::vertex_iterator VertexIterator;
typedef boost::graph_traits<Graph>::edge_iterator EdgeIterator;
typedef boost::graph_traits<Graph>::adjacency_iterator AdjacencyIterator;

这是我的GraphService Headerfile的一部分：

#include "Graph.h"
class GraphService {
    private:
        Graph g;
    public:
        std::vector<int> get_adjacent(int i);
}

困扰我的部分是：

#include "Graph.h"

GraphService::GraphService(Graph graph) {
g = graph
}



std::vector<int> GraphService::get_adjacent(int i) {
    AdjacencyIterator first, last;
    std::vector<int> vertex_vector;
    vertex_vector.push_back(i);

    for (tie(first,last) = adjacent_vertices(i,g); first != last; ++first) {

        vertex_vector.push_back(g[*first].id);
    }

    return vertex_vector;
}

我使用UnitTests测试了这个函数并且测试工作正常，但在我的编译器输出中，我看到以下错误消息;

/bin/sh: line 7: 20148 Segmentation fault      build/Debug/GNU-Linux-x86/tests/TestFiles/f2

这似乎是指adjacency_iterator的错误。调试器告诉我，错误发生了，因为迭代器是最后一次。

我试图在脚本中运行相同的代码，其中图的创建和adjacent_vertices上的迭代在同一个函数中。一切都在那里正常工作。

有人可以帮忙吗？

提前致谢！

Answer 1

我同意，特别是与您之前的问题有关，您可能在显示的代码之外有错误（Undefined Behaviour？）。

显示的代码可以正常工作，请参阅 SSCCE ：

<强> Live On Coliru

#include <boost/graph/adjacency_list.hpp>
#include <boost/multi_array.hpp>

using namespace boost;

struct vertex_info {
    int id = []{ static int s_gen = 0; return ++s_gen; }();
};

struct edge_info {
};

struct graph_info {
};

typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, vertex_info, edge_info, graph_info, boost::listS>
    Graph;
typedef boost::graph_traits<Graph>::vertex_descriptor VertexDescriptor;
typedef boost::graph_traits<Graph>::edge_descriptor EdgeDescriptor;
typedef boost::graph_traits<Graph>::vertex_iterator VertexIterator;
typedef boost::graph_traits<Graph>::edge_iterator EdgeIterator;
typedef boost::graph_traits<Graph>::adjacency_iterator AdjacencyIterator;
typedef multi_array<int, 3> array3i;

class GraphService {
  private:
    Graph g;

  public:
    GraphService(Graph graph) { g = graph; }
    std::vector<int> get_adjacent(int i);
};

std::vector<int> GraphService::get_adjacent(int i)
{
    AdjacencyIterator first, last;
    std::vector<int> vertex_vector;
    vertex_vector.push_back(i);

    for (tie(first, last) = adjacent_vertices(i, g); first != last; ++first) {
        vertex_vector.push_back(g[*first].id);
    }

    return vertex_vector;
}

#include <iostream>
#include <boost/graph/random.hpp>
#include <random>

int main() {
    std::mt19937 prng { std::random_device{}() };
    Graph example;
    generate_random_graph(example, 100, 200, prng);

    GraphService let_clone_that(example);

    std::cout << "adjacent to 42: ";
    for(int v: let_clone_that.get_adjacent(42))
        std::cout << v << " ";
}

打印，例如

adjacent to 42: 42 71 38 3 14

使用adjacency_iterator进行C ++ boost图库分割错误

1 个答案: