带头结点的链表及菜单 2018年12月26日
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#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
/*定义结构体*/
struct student {
int num;
float score;
struct student *next;
};
/*初始化链表*/
struct student *Init_List() {
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;
}
/*创建带头结点的链表*/
struct student *create_head(struct student *head) {
int sno;
float score;
struct student *p,*q;
q=head;
while(q->next) q=q->next;
printf("请输入学号和成绩，学号输入-1结束: ");
scanf("%d%f",&sno,&score);
while(sno>=0) {
p=(student *)malloc(sizeof(student));
p->num=sno;
p->score=score;
q->next=p;
q=p;
scanf("%d%f",&sno,&score);
}
q->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*/
void 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 {
s->next=p->next;
p->next=s; //连接结点,这两条语句不要写反
}
}
/*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,int num) {
struct student *p=head->next;
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;
return p;
}
/*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) {
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*/
void 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) return;
p2->next=p1->next;
free(p1);
}
//获取链表长度（不包括头节点）
int Size_List(struct student* head) {
struct student* temp = head->next;
int size = 0;
while (temp) {
size++;
temp = temp->next;
}
return size;
}
//链表的排序（冒泡）
void Sort_List(struct student* head) {
int i,j, n = Size_List(head);
struct student *p;
int t;
float r;
for (i=1; i<n; i++) {
p=head->next;
for (j=1; j<=n-i; j++) {
if (p->score > p->next->score) {
t=p->num,p->num=p->next->num,p->next->num=t;
r=p->score,p->score=p->next->score,p->next->score=r;
}
p=p->next;
}
}
}
/*完整的有头结点链表操作程序*/
int main() {
struct student *p , *head ;
char c;
int num ;
float score ;
printf("有头结点链表操作程序:\n");
head=Init_List();
while(1) {
printf("\nC:创建链表 I:插入结点(自动升序) P:输出链表 "
" S:查找结点 D:删除结点 X:排序 E:释放链表并退出程序! \n ");
c=getch();
switch(c) {
case 'I':
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 'C':
case 'c':
head=create_head(head);
break;
case'P':
case 'p':
print(head);
break;
case'S':
case 's':
printf("输入要查找的学号\n");
scanf("%d",&num);
p=search(head,num);
if (p) {
printf("该学生信息为： ");
printf("num=%d,score=%f\n",p->num,p->score);
} else
printf("该学生不存在\n");
break;
case'D':
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 'X':
case 'x':
Sort_List(head);
break;
case 'E':
case 'e':
free_list(head);
exit (0);
}
}
return 0;
}