文章目录
下面实现上一节单链表的插入和删除操作
LinkList.h(未优化)
#ifndef __LINK_LIST_
#define __LINK_LIST_
namespace DTlib
{
template<class T>
class LinkList
{
protected:
struct Node
{
T value;
Node* next;
};
mutable Node m_header;
int m_length;
public:
LinkList();
~LinkList();
bool insert(int i,T& e);
bool remove(int i);
bool set(int i, T& e);
T get(int i) const;
int length() const;
void clear();
};
}
#endif
LinkList.cpp(未优化)
#include "LinkList.h"
#include <iostream>
using namespace DTlib;
using namespace std;
template<class T>
LinkList<T>::LinkList()
{
m_header.next = NULL;
m_length = 0;
}
template<class T>
bool LinkList<T>::insert(int i,T&e)
{
bool ret = (i >= 0) && (i <= m_length);
if (ret)
{
Node* node = new Node();
if (node != NULL)
{
Node* pre = &m_header;
for (int pos = 0; pos < i; pos++)
{
pre = pre->next;
}
node->value = e;
node->next = pre->next;
pre->next = node;
}
else
{
cout << "no memery to malloc" << endl;
}
}
m_length++;
return ret;
}
template<class T>
bool LinkList<T>::remove(int i)
{
bool ret = (i >= 0) && (i <= m_length);
if (ret)
{
Node* pre = &m_header;
for (int pos = 0; pos < i; pos++)
{
pre = pre->next;
}
Node* toDel = pre->next;
pre->next = toDel->next;
delete toDel;
m_length--;
}
return ret;
}
template<class T>
bool LinkList<T>::set(int i, T& e)
{
bool ret = (i >= 0) && (i <= m_length);
if (ret)
{
Node* pre = &m_header;
for (int pos = 0; pos < i; pos++)
{
pre = pre->next;
}
pre->next->value = e;
}
return ret;
}
template<class T>
T LinkList<T>::get(int i) const
{
bool ret = (i >= 0) && (i <= m_length);
T e;
if (ret)
{
Node* pre = &m_header;
for (int pos = 0; pos < i; pos++)
{
pre = pre->next;
}
e = pre->next->value;
}
return e;
}
template<class T>
int LinkList<T>::length() const
{
return m_length;
}
template<class T>
void LinkList<T>::clear()
{
while(m_header.next != NULL)
{
Node* toDel = m_header.next;
m_header.next = toDel->next;
delete toDel;
}
m_length = 0;
}
template<class T>
LinkList<T>::~LinkList()
{
clear();
}
int main()
{
LinkList<int> l;
for (int i = 0; i < 5; i++)
{
l.insert(i,i);
}
for (int i = 0; i < l.length(); i++)
{
cout << l.get(i) << endl;
}
return 0;
}
单链表的优化
1.头结点的优化
单链表在构建时必须先创建头结点，头结点在创建时必须调用具体类型的构造函数，如果具体类型的构造函数抛出异常，则单链表对象将构建失败，并会传递具体类型构造函数的异常
class Test
{
public:
Test()
{
throw 0;
}
};
int main()
{
LinkedList<Test> l;
return 0;
}
创建一个内存布局与链表相同的头结点，在创建头结点的时候不会调用构造函数,
mutable struct:public Object
{
char reserved[sizeof(T)];//占位空间，与T类型的大小一样
Node* next;
}m_header;
2、目标位置定位的代码优化
单链表的操作中经常需要找到目标位置，可以将此部分代码独立出来。
Node* position(int index)const
{
//类型转换
Node* ret = reinterpret_cast<Node*>(&m_header);
for(int i = 0; i < index; i++)
{
ret = ret->next;
}
return ret;
}
3.增加查找操作
增加一个find操作，查找第一个出现查找值的地方
virtual int find(const T& value)const = 0;
int find(const T& value)const
{
int ret = -1;
Node* node = m_header.next;
int i = 0;
while(node)
{
if(node->value == value)
{
ret = i;
break;
}
else
{
node = node->next;
i++;
}
}
return ret;
}
4.LinkList.h(已优化)
#ifndef __LINK_LIST_
#define __LINK_LIST_
namespace DTlib
{
template<class T>
class LinkList
{
public:
struct Node
{
T value;
Node* next;
};
mutable struct
{
char reverse[sizeof(T)];
Node* next;
} m_header;
int m_length;
Node* position(int i)const
{
Node* pre = reinterpret_cast<Node*>(&m_header);
for (int pos = 0; pos < i; pos++)
{
pre = pre->next;
}
return pre;
}
public:
LinkList();
~LinkList();
bool insert(int i,T& e);
bool remove(int i);
bool set(int i, T& e);
T get(int i) const;
int length() const;
void clear();
};
}
#endif
5.LinkList.cpp(已优化)
#include "LinkList.h"
#include <iostream>
using namespace DTlib;
using namespace std;
template<class T>
LinkList<T>::LinkList()
{
m_header.next = NULL;
m_length = 0;
}
/*template<class T>
Node* LinkList<T>::position(int i)const
{
Node* pre = reinterpret_cast<Node*>(&m_header);
for (int pos = 0; pos < i; pos++)
{
pre = pre->next;
}
return pre;
}*/
template<class T>
bool LinkList<T>::insert(int i,T&e)
{
bool ret = (i >= 0) && (i <= m_length);
if (ret)
{
Node* node = new Node();
if (node != NULL)
{
Node* pre = reinterpret_cast<Node*>(&m_header);
pre = position(i);
node->value = e;
node->next = pre->next;
pre->next = node;
}
else
{
cout << "no memery to malloc" << endl;
}
}
m_length++;
return ret;
}
template<class T>
bool LinkList<T>::remove(int i)
{
bool ret = (i >= 0) && (i <= m_length);
if (ret)
{
Node* pre = reinterpret_cast<Node*>(&m_header);
pre = position(i);
Node* toDel = pre->next;
pre->next = toDel->next;
delete toDel;
m_length--;
}
return ret;
}
template<class T>
bool LinkList<T>::set(int i, T& e)
{
bool ret = (i >= 0) && (i <= m_length);
if (ret)
{
Node* pre = reinterpret_cast<Node*>(&m_header);
pre = position(i);
pre->next->value = e;
}
return ret;
}
template<class T>
T LinkList<T>::get(int i) const
{
bool ret = (i >= 0) && (i <= m_length);
T e;
if (ret)
{
Node* pre = reinterpret_cast<Node*>(&m_header);
pre = position(i);
e = pre->next->value;
}
return e;
}
template<class T>
int LinkList<T>::length() const
{
return m_length;
}
template<class T>
void LinkList<T>::clear()
{
while(m_header.next != NULL)
{
Node* toDel = m_header.next;
m_header.next = toDel->next;
delete toDel;
}
m_length = 0;
}
template<class T>
LinkList<T>::~LinkList()
{
clear();
}
int main()
{
LinkList<int> l;
for (int i = 0; i < 5; i++)
{
l.insert(i,i);
}
for (int i = 0; i < l.length(); i++)
{
cout << l.get(i) << endl;
}
return 0;
}
结果为：
0
1
2
3
4
position函数在类内实现会报下面错误，哪位大佬可以解答一下
