我对Heap.h和cpp文件中的前一个代码进行了一些更改，以及PQ ..并添加了一个PQ.cpp。我正在尝试创建一个堆ADT，它将成为优先级队列的Heap实现。我只是想在堆声明中添加一个peek函数，但我不能没有收到错误。 其中包括这些错误。
架构x86_64的未定义符号： “PrecondViolatedExcep :: PrecondViolatedExcep（std :: __ 1 :: basic_string，std :: __ 1 :: allocator＆gt; const＆amp;）”，引自： PQ.o中的pqClass :: peek（）const Heap.o中的heapClass :: peekTop（）const “itemClass :: GetDirection（）const”，引自： main.o中的enqRequest（int，int，int，bool，itemClass＆amp;，pqClass，pqClass） ld：找不到架构x86_64的符号 clang：错误：链接器命令失败，退出代码为1（使用-v查看调用）
Heap.h
BeginReceiveFrom()Heap.cpp
// *********************************************************
// Header file Heap.h for the ADT heap.
// *********************************************************
#include "Data.h" // definition of itemClass
#pragma once
const int MAX_HEAP = 20;
typedef itemClass keyType;
typedef itemClass heapItemType;
class heapClass
{
public:
heapClass(); // default constructor
// copy constructor and destructor are
// supplied by the compiler
// heap operations:
virtual bool HeapIsEmpty() const;
// Determines whether a heap is empty.
// Precondition: None.
// Postcondition: Returns true if the heap is empty;
// otherwise returns false.
virtual void HeapInsert(const heapItemType& NewItem,
bool& Success);
// Inserts an item into a heap.
// Precondition: NewItem is the item to be inserted.
// Postcondition: If the heap was not full, NewItem is
// in its proper position and Success is true;
// otherwise Success is false.
virtual void HeapDelete(heapItemType& RootItem,
bool& Success);
// Retrieves and deletes the item in the root of a heap.
// This item has the largest search key in the heap.
// Precondition: None.
// Postcondition: If the heap was not empty, RootItem
// is the retrieved item, the item is deleted from the
// heap, and Success is true. However, if the heap was
// empty, removal is impossible and Success is false.
heapItemType peekTop() const throw(PrecondViolatedExcep);
protected:
void RebuildHeap(int Root);
// Converts the semiheap rooted at index Root
// into a heap.
private:
heapItemType Items[MAX_HEAP]; // array of heap items
int Size; // number of heap items
}; // end class
// End of header file.
优先级队列 PQ.h
// *********************************************************
// Implementation file Heap.cpp for the ADT heap.
// *********************************************************
#include "Heap.h" // header file for heap
heapClass::heapClass() : Size(0)
{
} // end default constructor
bool heapClass::HeapIsEmpty() const
{
return bool(Size == 0);
} // end HeapIsEmpty
void heapClass::HeapInsert(const heapItemType& NewItem,
bool& Success)
// Method: Inserts the new item after the last item in the
// heap and trickles it up to its proper position. The
// heap is full when it contains MAX_HEAP items.
{
Success = bool(Size < MAX_HEAP);
if (Success)
{ // place the new item at the end of the heap
Items[Size] = NewItem;
// trickle new item up to its proper position
int Place = Size;
int Parent = (Place - 1)/2;
while ( (Parent >= 0) &&
(Items[Place].Key() > Items[Parent].Key()) )
{ // swap Items[Place] and Items[Parent]
heapItemType Temp = Items[Parent];
Items[Parent] = Items[Place];
Items[Place] = Temp;
Place = Parent;
Parent = (Place -1 )/2;
} // end while
++Size;
} // end if
} // end HeapInsert
void heapClass::HeapDelete(heapItemType& RootItem,
bool& Success)
// Method: Swaps the last item in the heap with the root
// and trickles it down to its proper position.
{
Success = bool(!HeapIsEmpty());
if (Success)
{ RootItem = Items[0];
Items[0] = Items[--Size];
RebuildHeap(0);
} // end if
} // end HeapDelete
void heapClass::RebuildHeap(int Root)
{
// if the root is not a leaf and the root's search key
// is less than the larger of the search keys in the
// root's children
int Child = 2 * Root + 1; // index of root's left
// child, if any
if ( Child < Size )
{ // root is not a leaf, so it has a left child at Child
int RightChild = Child + 1; // index of right child,
// if any
// if root has a right child, find larger child
if ( (RightChild < Size) &&
(Items[RightChild].Key() > Items[Child].Key()) )
Child = RightChild; // index of larger child
// if the root's value is smaller than the
// value in the larger child, swap values
if ( Items[Root].Key() < Items[Child].Key() )
{ heapItemType Temp = Items[Root];
Items[Root] = Items[Child];
Items[Child] = Temp;
// transform the new subtree into a heap
RebuildHeap(Child);
} // end if
} // end if
// if root is a leaf, do nothing
} // end RebuildHeap
heapItemType heapClass::peekTop() const throw(PrecondViolatedExcep)
{
if (HeapIsEmpty())
throw PrecondViolatedExcep("Attempted peek into an empty heap.");
return Items[0];
} // end peekTop
PQ.cpp
// *********************************************************
// Header file PQ.h for the ADT priority queue.
// Heap implementation.
// *********************************************************
#include "Heap.h" // ADT heap operations
typedef heapItemType pqItemType;
class pqClass
{
public:
// default constructor, copy constructor, and
// destructor are supplied by the compiler
// priority-queue operations:
virtual bool PQueueIsEmpty() const;
virtual void PQueueInsert(const pqItemType& NewItem,
bool& Success);
virtual void PQueueDelete(pqItemType& PriorityItem,
bool& Success);
pqItemType peek() const throw(PrecondViolatedExcep);
private:
heapClass H;
}; // end class
// End of header file.
答案 0 :(得分：1)
您需要在.cpp文件中的函数签名中添加const，以便它与.h文件中的签名匹配。
答案 1 :(得分：0)
你在PQ.h中创建了一个abstruct类的对象：
heapClass H;
你也试图只在堆空了
时访问一个元素heapItemType heapClass::peekTop(){
if (HeapIsEmpty())
return heapItemType[0];
}
你需要这样的东西（万一你的类型是一个指针）：
heapItemType heapClass::peekTop(){
if (HeapIsEmpty()) {
return nullptr;
}
return heapItemType[0];
}
或者你需要某种无效的对象，你可以在空堆的情况下返回
答案 2 :(得分：0)
通过查看您的代码我可以告诉您，您已经定义了heapClass的方法：
virtual heapItemType peekTop() const =0;
这被声明为纯虚函数，因为您在类中的声明中将其设置为等于0。这将导致您的heapClass变得抽象。我在pqClass中看到的所有内容都是存储heapClass类型的对象。我在这里看不到任何继承，这是您可能遇到构建或编译器错误的原因之一。如果不继承它，则不能将类中的方法或函数声明为纯虚拟。我不知道这是不是你想要的。但是就目前而言，你的heapClass是抽象的，这种方法声明！
您需要从其声明中删除= 0，或者从此类继承，派生类将使用override指令实现此函数。 Anon Mail也是正确的，你还需要在实现文件中将方法声明为const，而Andrew Lavq对你的函数的实际实现有一个有效的观点。