链表练习（数据结构线性表test2）

// StudentTest2.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <iomanip>
using namespace std;
struct Student
{
 int num;
 float score;
 Student *next;          //next指向Student结构体变量
};

Student *Creat_front(); //按头插法创建链表,以-1 -1作为输入结束标志
void Output(Student *head); //输出链表全部元素

Student *Creat_rear();      //按尾插法创建链表,以-1 -1作为输入结束标志
Student *Locate(Student *head,int num); //给定学号,查找元素位置

void  LinkInsert(Student *head, Student *p); //向p指向的元素后插入一个新输入的元素

Student  *LinkDelete(Student *head, int num); //删除学号为num的元素

void Menu();  //简单的显示菜单

//定义一个全局变量记录链表的长度
int length;
void main()
{
 int choose,num;
 Student *head,*p;
 
 Menu();       //显示菜单选项
 cin>>choose;
 while(choose!=0)
 {
  switch(choose)
  {
  case 1:   //头插法创建链表,与2不能同时使用
   head=Creat_front();
   break;
  case 2:   //尾插法创建链表
   head=Creat_rear();
   break;
  case 3:   //链表输出
   Output(head);
   break;  
  case 4:   //查找元素
   cout<<"输入待查找NUM: ";
   cin>>num;
   p=Locate(head,num);
   if(p==NULL)
    cout<<"没有NUM为: "<<num<<"的同学信息"<<endl;
   else
    cout<<"NUM为: "<<num<<"的同学成绩为: "<<p->score<<endl;
   break;
    
  case 5:   //插入元素
   LinkInsert(head,p);  //在查找到的元素后,插入一个新元素
   break;
   
  case 6:   //删除元素
   cout<<"输入要删除的NUM: ";
   cin>>num;
   head=LinkDelete(head,num);
   break;
  
  }
  Menu();
  cin>>choose;
 }
  
}

Student *Creat_rear(){
	  Student *p1,*p2,*header;
 p1=p2=new Student;
 cout<<"请输入学号和姓名："<<endl;
 cin>>p1->num>>p1->score;
 header=NULL;
 header=p1;
 p2=p1;
 while(p1->num!=-1&&p1->score!=-1)
 {  
	length++;
  p1->next=p2;
  p2=p1;
  p1=new Student;
  cout<<"请输入学号和姓名："<<endl;
  cin>>p1->num>>p1->score;
 }

 header->next=NULL;
 return(p2);
}

Student *Creat_front(){//定义tou插法
Student *p1,*p2,*header;
		 p1=p2=new Student;
		 cout<<"请输入学号和姓名："<<endl;
		 cin>>p1->num>>p1->score;
		 header=NULL;
		 header=p1;
	 while(p1->num!=-1&&p1->score!=-1)
	 {   
		 length++;
		  p2=p1;
		  p1=new Student;
		  p2->next=p1;
		  cout<<"请输入学号和姓名："<<endl;
		  cin>>p1->num>>p1->score;
	 }
	 p1=NULL;
	 p2->next=NULL;
return header;
}

//定义输出函数
void Output(Student *head){ 
	Student *p1;
	p1=head;
	if(head!=NULL){		
		for(;;){
			    cout<<p1->num<<endl;
		        cout<<p1->score<<endl;
			if(p1->next!=NULL){
				
		        p1=p1->next;	
			}else{
			break;
			}					
		}		
	}
}
//定义查找函数
Student *Locate(Student *head,int num){
	Student *p1;
	p1=head;
	do{
		if(p1->num!=num){
			p1=p1->next;
		
		}else if(p1->num==num){
			return p1;
		}
	}while(p1->next!=NULL);
return NULL;
}
//定义函数
void  LinkInsert(Student *head, Student *p)
{

 Student *p0,*p1,*p2,*p3;
 p3=new Student();
 cout<<"请输入你要插入学生的学号和成绩："<<endl;
 cin>>p3->num>>p3->score;
 p1=head;
 p0=p;
 if(head==NULL)
 {head=p0;p0->next=NULL;}
 else{
  while((p0->num!=p1->num)&&(p1->next!=NULL))
  {
      p1=p1->next;
      p2=p1->next; 
  }     
  if(p0->num==p1->num&&p0->score==p1->score)
  {
   p2=p1->next;
   p1->next=p3;
   p3->next=p2;
   length=length+1;
  }
  else
  {
   cout<<"找不到匹配项"<<endl;
  }
 }

}

void Menu()
{
 cout<<"-----------菜单----------"<<endl;
 cout<<"   1. 头插法创建链表"<<endl;
 cout<<"   2. 尾插法创建链表"<<endl;
 cout<<"   3. 链表输出"<<endl;
 cout<<"   4. 查找元素"<<endl;
 cout<<"   5. 插入元素"<<endl;
 cout<<"   6. 删除元素"<<endl;
 cout<<"   0. 退出"<<endl;
 cout<<"-------------------------"<<endl;
 cout<<"请选择: ";

}
//定义删除函数
Student  *LinkDelete(Student *head, int num){
	Student *p1,*p2;
 if(head==NULL)
 {
  cout<<"这是一个空表."<<endl;
  return(head);
 }
 p1=head;
 while(num!=p1->num&&p1->next!=NULL)
 {
  p2=p1;
  p1=p1->next;
 }
 if(num==p1->num)
 {
  if(p1==head)
	  head=p1->next;
  else
     p2->next=p1->next;
  delete p1;
  cout<<"删除学号为:"<<num<<"成功"<<endl;
  length=length-1;
 }
 else cout<<"找不到学号"<<endl;
 return(head);
}