我已经有人工投入它的列表的程序,它只是一堆名字扔在这样的复制当我尝试通过我的拷贝构造函数和赋值运算符运行已经创建的列表时,列表就会出现在“”(在isEmpty函数中定义)C++列表不是通过复制构造函数或赋值运算符
忽略所有“TODO”注释点,我。
也有一些随机的cout语句,我用于调试目的,并希望保持在那里,直到一切正常工作。
下面是相关代码:
List.h
class Node;
class List
{
public:
List();
List(const char* p);
//Copy constructor
List(const List& str);
//Deep Copy
List& operator=(const List& str);
~List();
void Clear();
//Adds to the front
void PushFront(std::string data);
//adds to the back
void PushBack(std::string data);
//removes from the front
void PopFront();
//removes from the back
void PopBack();
//gets the back value
std::string& Back() const;
//gets the from value
std::string& Front() const;
bool Empty() const {return m_pFront == 0;}
ostream& OutPut(ostream& os);
private:
Node* m_pFront;
Node* m_pBack;
char* m_pData;
};
List.cpp
List::List() : m_pFront(0), m_pBack(0), m_pData(0)
{}
List::~List()
{
Clear();
}
void List::Clear()
{
//delete
if(!m_pFront)
{
return;
}
delete m_pFront;
delete m_pData;
m_pFront = 0;
m_pBack = 0;
}
void List::PushFront(std::string data)
{
//create a new node
Node* p = new Node(data);
//Empty list
if(!m_pFront)
{
m_pFront = p;
m_pBack = p;
}
else //Not empty list
{
p -> m_pNext = m_pFront;
m_pFront -> m_pPrev = p;
m_pFront = p;
}
}
void List::PushBack(std::string data)
{
Node* p = new Node(data);
if(!m_pBack)
{
m_pFront = p;
m_pBack = p;
}
else
{
p -> m_pPrev = m_pBack;
m_pBack -> m_pNext = p;
m_pBack = p;
}
}
void List::PopFront()
{
if(m_pFront == 0)
{
//TODO: we need to handle this problem
return;
}
if(m_pBack == m_pFront)
{
Clear();
return;
}
Node* p = m_pFront;
m_pFront = m_pFront -> m_pNext;
p -> m_pNext = 0;
m_pFront -> m_pPrev = 0;
delete p;
}
void List::PopBack()
{
if(m_pBack == 0)
{
//TODO: we need to handle this problem
return;
}
if(m_pBack == m_pFront)
{
Clear();
return;
}
Node* p = m_pBack;
m_pBack = m_pBack -> m_pPrev;
p -> m_pPrev = 0;
m_pBack -> m_pNext = 0;
delete p;
}
ostream& List::OutPut(ostream& os)
{
if(Empty() == true)
{
os << "<empty>";
}
else
{
m_pFront -> OutputNode(os);
}
return os;
}
std::string& List::Back() const
{
if(m_pBack == 0)
{
//TODO: we need to handle this problem
}
return m_pBack -> GetData();
}
std::string& List::Front() const
{
if(m_pFront == 0)
{
//TODO: we need to handle this problem
}
return m_pFront -> GetData();
}
//Copy Constructor
List::List(const List& str)
{
if(str.m_pData)
{
m_pData = new char[strlen(str.m_pData) + 1];
strcpy(m_pData, str.m_pData);
}
else
{
m_pData = 0;
}
}
//Deep copy
List& List::operator=(const List& str)
{
//Check for self assignment
if(this == &str)
{
return *this;
}
//Deallocate any value the string is holding
delete [] m_pData;
//Now we need to deep copy m_pData
if(str.m_pData)
{
//Allocate memory for the copy
m_pData = new char[strlen(str.m_pData) + 1];
//Copy the parameter to the newly allocated memory
strcpy(m_pData, str.m_pData);
}
else
{
m_pData = 0;
}
return *this;
}
你的类没有构造,你正在使用Empty()== true,它不会给出明确的结果。 – doptimusprime
尝试'str.Empty()'而不是 – user1520427
str.Empty()只会导致程序崩溃,它不会在之前。 –