2、#include
#include
#include
/*定义结构体*/
struct student
{
int num;
float score;
struct student *next;
};
/*创建一个只有头结点的空链表*/
struct student *create_head()
{
struct student *head;
head=(struct student*)malloc(sizeof (struct student) );
if(head==NULL) //小心别漏这个
{
printf("申请头结点失败!\n");
return NULL;
}
head->next=NULL;
return head;
}
/*将s指向的结点插入链表,使链表保持升序,并返回头结点*/
struct student *insert(struct student *head,struct student *s)
{
struct student *p=head;
while(p->next!=NULL&&s->score>p->next->score)//特别注意&&左右不能写反,若s最大,最后p->next=NULL,p->next->score运行出错
p=p->next;
if(p->next==NULL) //s->score最大的情况 //其实两种情况可以并在一块写
{
p->next=s; //连接结点
s->next=NULL; //p->next就等于NULL
}
else
{
p->next=s; //连接结点
s->next=p->next;
}
return head ;
}
/*查找符合条件的结点,并返回指向该结点的指针*/
struct student *search(struct student *head)
{
struct student *p=head->next;
int num;
printf("请输入要查找学生的学号:\n");
scanf("%d",&num);
while(p!=NULL&&p->num!=num) //特别注意两条件不能写反,若写反最后p指向NULL时p->num找不到 运行出错
p=p->next;
if(p==NULL) //特别注意两个if不能调换,若调换最后p指向NULL时p->num运行出错
{
printf("找不到符合条件的结点!!!");
return NULL; //查找不到返回空指针
}
if(p->num==num)
{
printf("找到符合条件的结点\n该结点为%d\t%f",p->num,p->score);
return p; //返回查找到的指针
}
}
/*输出链表各结点的值,也称对链表的遍历*/
void print(struct student *head)
{
struct student *p;
printf(" 链表如下: \n");
p=head->next;
while(p!=NULL)
{
printf("%d\t%.1f\n",p->num,p->score);
p=p->next;
}
}
/*释放链表*/
void free_list(struct student *head)
{
struct student *p=head ;
printf("释放链表:\n");
while(p!=NULL)
{
head=head->next;
free(p);
p=head;
}
printf("释放链表成功!\n");
}
/*删除链表中值为num的结点,并返回链表的首指针*/
struct student *delete_note(struct student *head,int num_x)
{
struct student *p1=head->next , *p2=head ;
while(p1!=NULL&&p1->num!=num_x) //特别注意&&左右条件不能调换,若调换如果p1指向NULL时p1->num运行出错
{
p2=p1;
p1=p1->next;
}
if(p1==NULL) //特别注意两个if不能调换,若调换如果p1指向NULL时,p1->num运行出错
printf("找不到符合删除要求的结点!!!\n");
if(p1->num==num_x)
{
p2->next=p1->next;
free(p1);
printf("结点删除成功!\n");
}
return head;
}
/*完整的有头结点链表操作程序*/
void main()
{
struct student *p , *head ;
char c;
int num ;
float score ;
printf("有头结点链表操作程序:\n");
head=create_head();
while(1)
{
printf("I:插入结点(自动升序) P:输出链表 S:查找结点 D:删除结点 E:释放链表并退出程序! ");
c=getch();
switch(c)
{
case'I':
printf("请分别输入要插入学生的学号和分数:\n");
scanf("%d%f",&num,&score);
p=(struct student*)malloc( sizeof(struct student) );
if(p==NULL)
{
printf("申请该结点失败!!!\n");
exit (0) ;
}
p->num=num; p->score=score; //给p赋值
insert(head,p);
printf("插入成功!\n");
break;
case'P':
print(head);
break;
case'S':
search(head);
break;
case'D':
printf("请输入要删除的学生的学号:\n");
scanf("%d",&num);
delete_note(head,num);
break;
case'E':
free_list(head);
exit (0);
}
}
}
