我正在创建一个实现findEdges（）函数的图形类。我使用std :: list＆lt;＆gt;使用邻接列表创建了图类。出于某种原因，当我运行我的驱动程序时，它会从文件中读取并正确创建图形。但是当我尝试选择一个点并使用findEdges（）时，它适用于第一个测试用例，但是在我之后读入的任何情况都会因某种原因返回一个空白集。
我将在下面发布一些代码：
class Graph
{
public:
// Non-Default Constructor
inline Graph(int num) : cap(num), numItems(0) { adjList = new list<Vertex[num]; }
// Copy constructor
inline Graph(const Graph & rhs) throw (const char *) { *this = rhs; }
// Destructor
inline ~Graph() {delete [] adjList;};
// Assignment operator
inline const Graph & operator = (const Graph & rhs) throw (const char *);
inline bool isEdge(const Vertex v1, const Vertex v2) const;
inline Set<Vertex> findEdges(CourseVertex theVertex);
inline void add(Vertex v1, Vertex v2);
inline void add(Vertex v1, Set<Vertex> groupV);
inline int size() const { return cap; }
inline void clear() {numItems=0;}
private:
list<Vertex> * adjList;
int cap;
int numItems;
};
查找边缘功能：
Set<Vertex> Graph::findEdges(CourseVertex theVertex)
{
Set<Vertex> edges;
// Loop through adjList array
for(int i = 0; i < cap; i++)
{
// Find v1's adjacency list
if (*adjList[i].begin() == theVertex)
{
//cerr << adjList[i].getText() << endl;
// Loop through adjacency list and find vertices
// containg and edge with theVertex
for(list<Vertex>::const_iterator it = adjList[i].begin();
it != adjList[i].end(); ++it)
{
++it;
edges.insert(*it);
}
}
// if have not found v2, return false (or if v1 is not in the list)
return edges;
}
}
驱动程序功能：*
void testFindAll()
{
try
{
Graph g1(28);
CourseVertex vFrom;
CourseVertex vTo;
{
Graph g2(g1.size());
// read the class dependencies from a file
// CS124 CS165 CIT225 ECEN160 |
ifstream fin("/home/cs235/week13/cs.txt");
assert(fin.good());
while (fin >> vFrom) // read the first vertex, the class
{
cerr << "First Vertex: " << vFrom.getText() << endl;
while (fin >> vTo){ // keep reading until the "|" is encountered
cerr << "Prerequisites: " << vTo.getText() << endl;
g2.add(vFrom, vTo);
}
fin.clear(); // clear the error state which came from the "|"
fin.ignore();
}
fin.close();
g1 = g2;
//TESTING CORRECT INPUT GRAPHS - DELETE
/**********************************************************************/
for (int i = 0; i < g2.size(); i++){
list<Vertex>::const_iterator it;
for( it = g2.adjList[i].begin(); it != g2.adjList[i].end(); ++it)
cout << *it << " ";
cout << endl;
}
for (int i = 0; i < g1.size(); i++){
list<Vertex>::const_iterator it;
for( it = g1.adjList[i].begin(); it != g1.adjList[i].end(); ++it)
cout << *it << " ";
cout << endl;
}
/**********************************************************************/
g2.clear();
}
// g2 is destroyed
// prompt for the next class
cout << "For the given class, the prerequisites will be listed:\n";
cout << "> ";
while (cin >> vFrom)
{
Set <Vertex> s = g1.findEdges(vFrom);
cerr << s << endl;
for (SetConstIterator <Vertex> it = s.cbegin(); it != s.cend(); ++it)
{
cout << '\t' << (vTo = *it) << endl;
}
cout << "> ";
}
}
catch (const char * error)
{
cout << error << endl;
}
}
这是我的输出。大括号之间的输出是边缘之前有多少个点。
所以我读的文件应该是这样的：
CS165 CS124 |
CS235 CS165 |
CS237 CS165 |
CS238 CS237 |
CS246 CS235 |
CS306 CS235 CS237 |
这就是我的输出：
For the given class, the prerequisites will be listed:
> CS165
{ CS124 }
CS124
> CS235
{ }
这是我的输出应该是这样的：
For the given class, the prerequisites will be listed:
> CS165
{ CS124 }
CS124
> CS235
{ CS165 }
CS165
由于某些cerr，我能够看到它正确地创建我的图形，具有正确的边缘和一切。出于某种原因，当我试图找到超出图形第一行的任何边缘时，我的findEdges（）函数返回一个空集。任何帮助表示赞赏。
作业运营商：
const Graph & Graph::operator = (const Graph & rhs) throw (const char *)
{
if (this != &rhs) // check that not self-assignment
{
//--Allocate a new array if necessary
if (cap != rhs.cap)
{
//delete [] adjList;
cap = rhs.cap;
adjList = new std::list<Vertex>[cap];
if (adjList == 0) // Check if memory available
{
std::cerr << "ERROR: Unable to allocate a new buffer for Vector\n";
}
}
//--- Copy rightHandSide's list elements into this new array
cap = rhs.cap;
for (int i = 0; i < cap; i++)
{
//std::cerr<<adjList[i]<<std::endl;
adjList[i] = rhs.adjList[i];
}
}
return *this;
}