链表的优点:
对表的操作都可以使用数组来实现,因为数组是动态指定的,但是还是需要对表的大小的最大值进行估计,通常要估计的大一些,这会浪费大量的空间,这是严重的局限,这可能会导致程序出错.由于存在许多未知的大小的表的情况下.通过使用链表可以有效地避免这样的问题.同时使用链表可以较方便和快捷的对表进行插入和删除,减少了线性开销.下面让我们了解和学会使用对链表的简单操作:
链表的基本使用(使用c/c++做例子):
通过这个题来对链表进行理解:
编写一个程序,能够输入学生的学号和分数,并将其输出,同时能够删除学生信息和添加学生信息(要求使用链表完成,能够输出,删除和添加链表元素)
创建链表:
这是使用链表的第一步,废话不多说,上代码
#include <iostream>
#define NULL 0
using std::cin;
using std::cout;
using std::endl;
//创建数据结构
struct student
{
long num; //学号
float score; //分数
student *next; //链表的指针
};
int count; //全局变量,计数
//创建链表
student *creat()
{
student *head; //head 链表头
student *p1,*p2;
count=0;
p1 = p2 = new student; //开辟新单元,使p1,p2指向它
cin >> p1->num >> p2->score;
head = NULL; //清空head
while(p1->num != 0)
{
count+=1;
//如果head==1,那么p1就赋值给head
if(count==1)
{
head = p1;
}
//否则就将p1链接给p2的结点
else
{
p2->next = p1;
}
p2 = p1;
p1 = new student; //将p1开辟新单元
cin >> p1->num >> p1->score;
}
//清空p2的结点
p2->next = NULL;
return head;
}
输出链表:
链表的输出p先指向第一个结点,输完第一个之后,盘指向第二个结点.以此类推.
head的值由实参传过来,在函数中从head所指向的第一个结点出发顺序输出各个结点.
//输出创建的链表
void print(student *head)
{
student *p;
cout << endl << "输出链表节点:" << endl;
p = head;
//如果head不是空的,那么输出p
if(head != NULL)
do
{
cout << p->num << " " << p->score << endl;
p = p->next;
}while(p != NULL);
}
删除链表元素:
从动态链表中删除一个结点,并不是真正将其从内存中抹除,是将这个结点从链表中分离.这里我们制定学号作为删除结点的标志.
//操作链表进行删除
student *del(student *head,long num)
{
student *p1,*p2;
if(head == NULL)
{
cout << "八嘎呀路,空链表还操作个蛇!" << endl;
return head;
}
p1 = head;
//当num不是p1指向的num,p1的结点不是空的
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;
cout << "删除:" << num <<endl;
count-=1;
}
}
else
{
cout << "找不到该结点:" << num;
}
return head;
}
添加链表元素:
对链表的插入是将一个结点插入到一个已有的链表中.
//插入链表元素
student *insert(student *head,student *stud)
{
student *p0,*p1,*p2;
p1 = head;
p0 = stud;
if(head == NULL)
{
head = p0;
p0->next = NULL;
}
else
{
while((p0->num > p1->num)&&(p1->next!=NULL))
{
p2 = p1;
p1 = p1->next;
}
if(p0->num <= p1->num)
{
if(head == p1)
head = p0;
else
{
p2->next = p0;
}
p0 -> next = p1;
}
else
{
p1->next = p0;
p0 -> next = NULL;
}
count+=1;
return head;
}
}
下面写出这个题目的完整程序:
#include <iostream>
#define NULL 0
using std::cin;
using std::cout;
using std::endl;
//创建数据结构
struct student
{
long num; //学号
float score; //分数
student *next; //链表的指针
};
//链表的创建,删除,插入,输出
student *creat();
void print(student *head);
student *del(student *head,long num);
student *insert(student *head,student *stud);
int count; //全局变量,计数
int main()
{
student *head,stu;
long del_num;
cout << "输入记录(学号和得分):" << endl;
head = creat();
print(head);
cout << endl << "输入删除的数字:";
cin >> del_num;
head = del(head,del_num);
print(head);
cout << endl <<"输入要插入的结点:";
cin >> stu.num >> stu.score;
head = insert(head,&stu);
print(head);
return 0;
}
//创建链表
student *creat()
{
student *head; //head 链表头
student *p1,*p2;
count=0;
p1 = p2 = new student; //开辟新单元,使p1,p2指向它
cin >> p1->num >> p2->score;
head = NULL; //清空head
while(p1->num != 0)
{
count+=1;
//如果head==1,那么p1就赋值给head
if(count==1)
{
head = p1;
}
//否则就将p1链接给p2的结点
else
{
p2->next = p1;
}
p2 = p1;
p1 = new student; //将p1开辟新单元
cin >> p1->num >> p1->score;
}
//清空p2的结点
p2->next = NULL;
return head;
}
//输出创建的链表
void print(student *head)
{
student *p;
cout << endl << "输出链表节点:" << endl;
p = head;
//如果head不是空的,那么输出p
if(head != NULL)
do
{
cout << p->num << " " << p->score << endl;
p = p->next;
}while(p != NULL);
}
//操作链表进行删除
student *del(student *head,long num)
{
student *p1,*p2;
if(head == NULL)
{
cout << "八嘎呀路,空链表还操作个蛇!" << endl;
return head;
}
p1 = head;
//当num不是p1指向的num,p1的结点不是空的
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;
cout << "删除:" << num <<endl;
count-=1;
}
}
else
{
cout << "找不到该结点:" << num;
}
return head;
}
//插入链表元素
student *insert(student *head,student *stud)
{
student *p0,*p1,*p2;
p1 = head;
p0 = stud;
if(head == NULL)
{
head = p0;
p0->next = NULL;
}
else
{
while((p0->num > p1->num)&&(p1->next!=NULL))
{
p2 = p1;
p1 = p1->next;
}
if(p0->num <= p1->num)
{
if(head == p1)
head = p0;
else
{
p2->next = p0;
}
p0 -> next = p1;
}
else
{
p1->next = p0;
p0 -> next = NULL;
}
count+=1;
return head;
}
}
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