(转)c语言_链表实例讲解(两个经典例子)

建立一个学生成绩的线性链表，对其实现插入，删除，输出，最后销毁。

#include <stdio.h>
#include <stdlib.h>

struct grade
{
int score;
struct grade *next;
};
typedef struct grade NODE; //typedef为C语言的关键字，作用是为一种数据类型定义一个新名字。
//使用typedef目的一般有两个，一个是给变量一个易记且意义明确的新名字，
//另一个是简化一些比较复杂的类型声明。
struct grade *create(); //创建链表
void insert(NODE *head,NODE *pnew,int i); //插入链表
void pdelete(NODE *head,int i); //删除列表
void display(NODE *head); //输出链表
void Pfree(NODE *head); //销毁链表

int main(int argc, char *argv[])
{
struct grade *head,*pnew;
head=create();
if(head==NULL)
return 0;
printf("输出创建的链表：");
display(head);
pnew=(NODE *)malloc(sizeof(NODE));
if(pnew==NULL)
{
printf("创建失败！");
return 0;
}
pnew->score=88;
insert(head,pnew, 3); //将新节点插入节点3的后面
printf("插入后的链表：");
display(head);
pdelete(head,3); //删除节点3
printf("删除后的链表：");
display(head);
Pfree(head);
return 0;
}

struct grade *create()
{
NODE *head,*tail,*pnew;
int score;
head=(NODE *)malloc(sizeof(NODE)); //创建头节点。
if(head==NULL) //创建失败返回
{
printf("创建失败！");
return NULL;
}
head->next=NULL; //头节点指针域置NULL
tail=head; // 开始时尾指针指向头节点
printf("输入学生成绩：");
while(1) //创建链表
{
scanf("%d",&score);
if(score<0) //成绩为负是退出循环
break;
pnew=(NODE *)malloc(sizeof(NODE)); //创建新节点
if(pnew==NULL) //创建失败返回
{
printf("创建失败！");
return NULL;
}
pnew->score=score; //新节点数据域存放输入的成绩
pnew->next=NULL; //新节点指针域置NULL
tail->next=pnew; //新节点插入到表尾
tail=pnew; //为指针指向当前的尾节点
}
return head; //返回创建链表的头指针
}
void insert(NODE *head,NODE *pnew,int i)
{
NODE *p;
int j;

p=head;
for(j=0;j<i&&p!=NULL;j++) //p指向要插入的第i个节点
p=p->next;
if(p==NULL) //节点i不存在
{
printf("与插入的节点不存在！");
return;
}

pnew->next=p->next; //插入节点的指针域指向第i个节点的后继节点
p->next=pnew; //犟第i个节点的指针域指向插入的新节点
}

void pdelete(NODE *head,int i)
{
NODE *p,*q;
int j;
if(i==0) //删除的是头指针，返回
return;
p=head;
for(j=1;j<i&&p->next!=NULL;j++)
p=p->next; //将p指向要删除的第i个节点的前驱节点
if(p->next==NULL) //表明链表中的节点不存在
{
printf("不存在！");
return;
}
q=p->next; //q指向待删除的节点
p->next=q->next; //删除节点i，也可写成p->next=p->next->next
free(q); //释放节点i的内存单元
}
void display(NODE *head)
{
NODE *p;
for(p=head->next;p!=NULL;p=p->next)
printf("%d ",p->score);
printf("\n");
}
void pfree(NODE *head)
{
NODE *p,*q;

p=head;
while(p->next!=NULL) //每次删除头节点的后继节点
{
q=p->next;
p->next=q->next;
free(q);
}
free (head); //最后删除头节点
}
void Pfree(NODE *head)
{
NODE *p,*q;
p=head;
while(p->next!=NULL)
{
q=p->next;
p->next=q->next;
free(q);
}
free(p);
}

转自：http://hi.baidu.com/y%C9%D9%B0%D7y/blog/item/fa9f1c5b1525b500367abe80.html

链表是C语言中比较难，但是又比较重要的数据结构，相信有很多人在为它而头痛哦。
我做了一个链表的程序，发出来与大家共享，希望大家能用得着。

#include <stdio.h>
#include <malloc.h>
#include <conio.h>
#include <stdlib.h>

//链表单元定义，链表相关变量
struct student
{
int id;
float score;
struct student *next;
} *head,*pthis;

//输入数据创建链表
void input()
{
struct student *tmp;
printf("\n\n请输入学生的信息以学号为0结束:\n");
do
{
printf("ID\t成绩\n");
if((tmp=(struct student*)malloc(sizeof(struct student)))==NULL)
{
printf("\n错误!不能申请所需的内存!\n");
exit(0);
}
scanf("%d\t%f",&tmp->id,&tmp->score);
tmp->next=NULL;
if(tmp->id!=0)
{
if(head==NULL)
{
head=tmp;
pthis=head;
}
else
{
pthis->next=tmp;
pthis=pthis->next;
}
}
}
while(tmp->id!=0);
free(tmp);
}

//搜索链表找到第一个符合条件的项目输出
void search(int id)
{
printf("\n\n查询结果\n");
printf("ID\t成绩\n");
printf("-------------------------------\n");
if(head==NULL)
{
printf("\n错误!没有数据!\n");
return;
}
pthis=head;
while(pthis!=NULL)
{
if(pthis->id==id)
{
printf("%d\t%.2f\n",pthis->id,pthis->score);
return;
}
else
{
pthis=pthis->next;
}
}
printf("\n没有找到!\n");
}

//列表输出链表中的所有项
void list()
{
printf("\n\n数据列表\n");
printf("ID\t成绩\n");
printf("-------------------------------\n");
if(head==NULL)
{
printf("错误,没有数据!\n");
return;
}
pthis=head;
while(pthis!=NULL)
{
printf("%d\t%.2f\n",pthis->id,pthis->score);
pthis=pthis->next;
}
}

//插入数据
void insert()
{
int i,p;
struct student *tmp;
if(head==NULL)
{
printf("\n\n数据不存在，无法插入!\n");
return;
}
printf("\n请输入插入点:\n");
scanf("%d",&p);
if(p<0)
{
printf("输入不合法!");
return;
}
printf("\n\n请输入学生的信息:\nID\t成绩\n");
if((tmp=(struct student*)malloc(sizeof(struct student)))==NULL)
{
printf("\n错误!不能申请所需的内存!\n");
exit(0);
}
scanf("%d\t%f",&tmp->id,&tmp->score);
tmp->next=NULL;
if(tmp->id!=0)
{
pthis=head;
if(p==0)
{
tmp->next=head;
head=tmp;
}
else
{
for(i=0;i<p-1;i++)
{
if(pthis->next->next==NULL)
{
printf("\n找不到插入点，您输入的数据太大!\n");
return;
}
pthis=pthis->next;
}
tmp->next=pthis->next;
pthis->next=tmp;
}
}
else
{
printf("\n数据无效!\n");
free(tmp);
}
}

//追加数据
void append()
{
struct student *tmp;
printf("\n\n请输入学生的信息:\nID\t成绩\n");
if((tmp=(struct student*)malloc(sizeof(struct student)))==NULL)
{
printf("\n错误!不能申请所需的内存!\n");
exit(0);
}
scanf("%d\t%f",&tmp->id,&tmp->score);
tmp->next=NULL;
if(tmp->id!=0)
{
if(head==NULL)
{
head=tmp;
}
else
{
pthis=head;
while(pthis->next!=NULL)
{
pthis=pthis->next;
}
pthis->next=tmp;
}
}
else
{
free(tmp);
printf("\n数据无效!\n");
}
}

//删除数据
void del()
{
int p,i;
struct student *tmp;
if(head==NULL)
{
printf("\n\n没有数据，无法删除!\n");
return;
}
printf("\n\n请输入要删除的记录号:\n");
scanf("%d",&p);
if(p<0)
{
printf("\n输入不合法!\n");
return;
}
if(p==0)
{
pthis=head;
head=pthis->next;
free(pthis);
pthis=head;
}
else
{
pthis=head;
for(i=0;i<p-1;i++)
{
pthis=pthis->next;
if(pthis->next==NULL)
{
printf("\n\n指定记录不存在，无法删除!\n");
return;
}
}
tmp=pthis->next;
pthis->next=pthis->next->next;
free(tmp);
}
}

//程序主函数
void main()
{
char command=0;
int id=0;

//主循环
do
{
printf("\n\n\t 菜单\n");
printf("-------------------------------\n");
printf("\ta,输入数据\n");
printf("\tb,查询记录\n");
printf("\tc,数据列表\n");
printf("\td,追加记录\n");
printf("\te,插入记录\n");
printf("\tf,删除记录\n");
printf("\tg,退出系统\n");
printf("-------------------------------\n");
printf("\t请选择:");
command=getch();

//命令处理
switch(command)
{
case 'a':
if(head==NULL)
{
input();
break;
}
else
{
printf("\n\n数据已经存在！\n");
break;
}
case 'b':
printf("\n\n要查询的ID:");
scanf("%d",&id);
search(id);
break;
case 'c':
list();
break;
case 'd':
append();
break;
case 'e':
insert();
break;
case 'f':
del();
break;
}
}
while(command!='g');
}

=====================

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

typedef struct student

{

int num;

char name[16];

struct student *next;

}node;

node *creat()//创建链表

{

int x;

int cycle = 1;

char stu_name[16];

node *head,*p,*s;

head =(node*)malloc(sizeof(node));

p = head;

while(cycle)

{

printf("please input the student number:");

scanf("%d",&x);

if(x != 0)

{

printf("please input the student name:");

scanf("%s",stu_name);

// printf("STU_NAME:%s/n", stu_name);

s = (node *)malloc(sizeof(node));

if(NULL == s)

{

exit(1);

}

s->num = x;

memcpy(s->name, stu_name, 16);

p->next = s;

p = s;

}

else

cycle = 0;

}

head = head->next;

p->next = NULL;

return head;

}

int length(node *head)//链表测长

{

int n = 0;

node *p;

p = head;

while(p != NULL)

{

n++;

p = p->next;

}

return (n);

}

node *insert(node *head, int num, int length)//链表插入,NUM表示在第几个位置插入

{

int n=num;

int i = 1;

node *p0,*p1,*p2;

p1 = head;

p0 = (node *)malloc(sizeof(node));

printf("please input the student number:");

scanf("%d", &p0->num);

printf("please input the student name:");

scanf("%s", &p0->name);

if(n == 1)//插入表头

{

p0->next = p1;

head = p0;

return (head);

}

while(i < n-1)//找到要插入的前置节点

{

p1 = p1->next;

i++;

}

p2 = p1->next;

p1->next = p0;

p0->next = p2;

if(n == length+1)//插入表尾

{

p1->next = p0;

p0->next = NULL;

}

return (head);

}

node *delete(node *head, int location, int length)//删除链表节点

{

int n = location;

int i = 1;

node *p1,*p2;

p1 = head;

if(n == 1)

{

head = p1->next;

free(p1);

return (head);

}

while(i < n-1)//找到要删除的节点的前置节点

{

p1 = p1->next;

i++;

}

if(n < length)

{

p2 = p1->next;

p1->next = p2->next;

free(p2);

}

if(n == length)

{

p2 = p1->next;

p1->next = NULL;

free(p2);

}

return (head);

}

void print(node *head)

{

while(head != NULL)

{

printf("students:%d/n", head->num);

printf("student name: %s/n", head->name);

head = head->next;

}

}

node *invert(node *head)//链表逆置

{

node *p1,*p2,*p3;

p1 = head;

p2 = p1->next;

while(p2)

{

p3 = p2->next;

p2->next = p1;

p1=p2;

p2=p3;

}

head->next = NULL;

head = p1;

return (head);

}

int main(int argc, char **argv)

{

int len,insert_num,del_num;

node *stu_node;

stu_node = creat();

print(stu_node);

len = length(stu_node);

printf("there are %d node/n", len);

printf("what dou you want to do?/n[a]打印链表 [b]逆置链表 [c]删除节点 [d]插入节点: ");

char ch,c;

c = getchar();//用于清除缓冲区中的/n字符

scanf("%c",&ch);

switch (ch)

{

case 'a': print(stu_node);

break;

case 'b': stu_node = invert(stu_node);

print(stu_node);

break;

case 'c':

printf("which node dou you want to detele?:");

scanf("%d", &del_num);

stu_node = delete(stu_node, del_num, len);

print(stu_node);

break;

case 'd':

printf("which location dou you want to insert:");

scanf("%d",&insert_num);

stu_node = insert(stu_node , insert_num, len);

print(stu_node);

break;

}

return 0;

}