单链表

#include<iostream>
using namespace std;
const int defaultSize = 20;
typedef int TypeData;
typedef struct list{
 TypeData data;
 list *next;
}list;

class SeqList {
  list *head;
  public:
   SeqList();
   SeqList(int sz);
   SeqList(SeqList & l);
   ~SeqList();
   //遍历单链表
   void TraverseList(void f(TypeData &));
   // 计算链表的长度
   int length();
   //返回单链表中指定序号的结点值
   TypeData GetElem(int pos);
   //在表的i位置后插入元素x
   void Insert( int i,TypeData & x);
   //删除表中i位置的元素x
   bool Delete( int addr, TypeData & x);
   //表是否为空
   bool IsEmpty();
};
/*
-----------链表实现部分-------------
------------------------------------
*/
//----------不带形参构造函数----------------
SeqList::SeqList()
{
 head=new list;
 head->next=NULL;
}
//-----------带一个形参构造函数--------------
SeqList::SeqList( int sz)
{
 int i=0;
 head=new list;
    list *p=head,*q;
    while(i<sz)
 {
  q= new list;
  cin>>q->data;
  p->next =q;
  p=p->next;
  i++;
    }
    p->next =NULL; 
}
//===========复制构造函数===================
SeqList::SeqList(SeqList& HL)
{
 head=new list;
 head->next=NULL;
 list *p2=HL.head->next,*p1=head,*q;
 while( p2)
 {
  q= new list;
  q->data=p2->data ;
  p1->next =q;
  p1=q;
  p2=p2->next ;
 }
 p1->next =NULL;
}
//----------析构函数--------------
SeqList::~SeqList()
{
 list *p=head->next ,*q;
 while(p)
 {
  q=p->next;
  free(p);
  p=q;
 }
}
//----------链表的长度-----------------------
int  SeqList::length()
{
 list*current=head->next;
 int i=0;
 while(current)
 {
  i++;
  current=current->next;
 }
 return i;
}
//----------//返回单链表中指定序号的结点值-------------
TypeData SeqList:: GetElem(int pos)
{
 if(pos<1||pos>length())
 {cerr<<"无效位置!\n";}
 else{
  list*current=head->next;
  int i=1;
  while(current)
  {
   if(i++==pos)return current->data ;
   current=current->next ;
  }
  return head->data;
 }
}
//----------在链表中插入元素x----------------------
void SeqList::Insert( int i ,TypeData & x)
{
 if(head==NULL||i==0)
 {
  list *newNode=new list;
  newNode->data=x;
  if(newNode==NULL){cerr<<"存储分配错误！\n";exit(1);}
  newNode->next=head->next;head->next=newNode;
 }else
 {
  list* current=head;
  for(int k=1;k<=i;k++)
   if(current==NULL)break;
   else current=current->next;
   if(current==NULL&&head!=NULL)
   {cerr<<"无效的插入位置！\n";}
   else
   {
    list* newNode=new list;
    newNode->data=x;
    if(newNode==NULL){cerr<<"存储分配错误！\n";exit(1);}
    newNode->next=current->next;
    current->next=newNode;
   }

 }
}
//------------删除表中i位置的元素x-------------------
bool SeqList:: Delete( int addr, TypeData & x)
{
 list *current,*del;
 if(addr<1)
 {del=head;head=head->next;}
 else
 {
  current=head->next;
  for(int k=1;k<addr-1;k++)
   if(current==NULL) break;
   else current=current->next;
   if(current==NULL||current->next==NULL)
   {cerr<<"无效的删除位置！\n";return false;}
   del=current->next;
   current->next=del->next;
 }
 x=del->data;delete del;
 return true;
}
//------------链表是否为空--------------------
bool SeqList::IsEmpty()
{
 return length()==0;
}
//------------遍历链表--------------------
void SeqList::TraverseList(void f(TypeData &))
{
 list*current=head->next;
 while(current)
 {
  f(current->data);
  current=current->next;
 }
}
//------------遍历的函数--------------------
void f(int &a)
{
 cout<<a<<" ";
}

//----------------main()---------------------
void main()
{
 int n,u,num;
 cout<<"构造单链表list1,请确定数组元素个数:";
 cin>>n;
 SeqList List1(n);
 List1.TraverseList(f);
 cout<<"链表的长度为:"<<List1.length()<<endl;
 cout<<"你想得到哪个元素:";
 int addrs;
 cin>>addrs;
 cout<<"你想得到的元素是:"<<List1.GetElem(addrs)<<endl;
 cout<<"你想在链表的第几个元素后插入元素(若在第一个前插入请按'0'):";
 cin>>u;
 cout<<"插入的元素为";
 cin>>num;
 List1.Insert(u,num);
 cout<<"新链表为:"<<endl;
 List1.TraverseList(f);
 int it,i;
 cout<<"你想删除第几个数:"<<endl;
    cin>>i;
 List1.Delete(i,it);
 cout<<"新链表为:"<<endl;
 List1.TraverseList(f);

}