学生信息链表，建立，插入，删除，遍历，查找，修改，最大（小）值，平均
/【例11-10】建立一个学生成绩信息（包括学号、姓名、成绩）的单向链表，学生数据按学号由小到大顺序排列，要求实现对成绩信息的插入、修改、删除和遍历操作。/
/* 用链表实现学生成绩信息的管理 */
include<stdio.h>
include<stdlib.h>
include<string.h>
struct stud_node{
int num;
char name[20];
int score;
struct stud_node next;
};
struct stud_node create_stu_doc(); /* 新建链表 /
struct stud_node insertdoc(struct stud_node * head, struct stud_node stud); / 插入 /
struct stud_node deletedoc(struct stud_node * head, int num); /* 删除 /
void print_stu_doc(struct stud_node head); /* 遍历 */
struct stud_node * find(struct stud_node * head, int num); /查找/
struct stud_node * modify(struct stud_node * head, int num, int score); /修改成绩/
struct stud_node * max(struct stud_node * head); /求最高分数的学生记录/
struct stud_node * min(struct stud_node * head); /求最低分数的学生记录/
double ave(struct stud_node * head); /求平均分/
void save(struct stud_node * head);
struct stud_node *read();
typedef struct stud_node *lnode;
lnode head,p;
int main(void)
{
struct stud_node head=null, p;
int choice, num, score;
char name[20];
int size = sizeof(struct stud_node);
do{
printf("1:create 2:insert 3:delete 4:print 5:modify 6:find 7:max 8:save 9:read 10:min 0:exit\n");
scanf("%d", &choice);
switch(choice){
case 1:
head = create_stu_doc();
break;
case 2:
printf("input num,name and score:\n");
scanf("%d%s%d", &num,name, &score);
p = (struct stud_node *) malloc(size);
p->num = num;
strcpy(p->name, name);
p->score = score;
head = insertdoc(head, p);
break;
case 3:
printf("input num:\n");
scanf("%d", &num);
head = deletedoc(head, num);
break;
case 4:
print_stu_doc(head);
break;
case 5:
printf("input num:\n");
scanf("%d", &num);
printf("input score:\n");
scanf("%d", &score);
head=modify(head,num,score);
break;
case 6:
printf("input num:\n");
scanf("%d", &num);
p=find(head,num);
if(p!=null)
printf("%d\t%s\t%d \n", p->num, p->name, p->score);
else
printf("not found %d\n",num);
break;
case 7:
p=max(head);
if(p!=null)
printf("%d\t%s\t%d \n", p->num, p->name, p->score);
else
printf("not found\n");
break;
case 8:
save(head);
break;
case 9:
head=read();
break;
case 10:
p=min(head);
if(p!=null)
printf("%d\t%s\t%d \n", p->num, p->name, p->score);
else
printf("not found\n");
break;
case 0:
break;
}
}while(choice != 0);
return 0;
}
/新建链表/
struct stud_node * create_stu_doc()
{
struct stud_node * head,*p;
int num,score;
char name[20];
int size = sizeof(struct stud_node);
head = null;
printf("input num,name and score:\n");
scanf("%d%s%d", &num,name, &score);
while(num != 0){ /* 学号0表示输入结束，且学号0对应的姓名和成绩都要输入 */
p = (struct stud_node *) malloc(size);
p->num = num;
strcpy(p->name, name);
p->score = score;
head = insertdoc(head, p); /* 调用插入函数 */
scanf("%d%s%d", &num, name, &score);
}
return head;
}
/* 插入操作 /
struct stud_node insertdoc(struct stud_node * head, struct stud_node stud)
{
struct stud_node ptr ,ptr1, ptr2;
ptr2 = head;
ptr = stud; /* ptr指向待插入的新的学生记录结点 */
if(head == null){ /* 原链表为空时的插入 */
head = ptr; /* 新插入结点成为头结点 */
head->next = null;
}
else{ /* 原链表不为空时的插入 */
while((ptr->num > ptr2->num) && (ptr2->next != null)){
ptr1 = ptr2; /* ptr1, ptr2各后移一个结点 */
ptr2 = ptr2->next;
}
if(ptr->num <= ptr2->num){
if(head == ptr2) head = ptr;/* 新插入结点成为头结点 */
else ptr1->next = ptr; /* 在ptr1与ptr2之间插入新结点 */
ptr->next = ptr2;
}
else{ /* 新插入结点成为尾结点 */
ptr2->next = ptr;
ptr->next = null;
}
}
return head;
}
/* 删除操作 /
struct stud_node deletedoc(struct stud_node * head, int num)
{
struct stud_node ptr1, ptr2;
if(head == null) /*链表空 */
return null;
else if(head->num == num){
/* 要被删除结点为表头结点 */
while(head != null && head->num == num){
ptr2 = head;
head = head->next;
free(ptr2);
}
}
else{
/* 要被删除结点为非表头结点 */
ptr1 = head;
ptr2 = head->next; /*从表头的下一个结点搜索所有符合删除要求的结点 */
while(ptr2 != null){
if(ptr2->num == num){ /* ptr2所指结点符合删除要求 */
ptr1->next = ptr2->next;
free(ptr2);
}
else
ptr1 = ptr2; /* ptr1后移一个结点 */
ptr2 = ptr1->next; /* ptr2指向ptr1的后一个结点 */
}
}
return head;
}
/遍历操作/
void print_stu_doc(struct stud_node * head)
{
struct stud_node * ptr;
if(head == null){
printf("\nno records\n");
return;
}
printf("\nthe students' records are: \n");
printf("num\tname\tscore\n");
for(ptr = head; ptr != null; ptr = ptr->next)
printf("%d\t%s\t%d \n", ptr->num, ptr->name, ptr->score);
}
struct stud_node * find(struct stud_node * head, int num) /查找/
{
struct stud_node *ptr;
if(head==null)
return null;
else
{
for(ptr=head;ptr!=null;ptr=ptr->next)/*for循环从head开始到null循环*/
if(ptr->num==num)
break;
return ptr;
}
}
struct stud_node * modify(struct stud_node * head, int num, int score)/修改通过查找学号修改成绩/
{
struct stud_node *ptr;
if(head==null)
return null;
else
{
for(ptr=head;ptr!=null;ptr=ptr->next)
if(ptr->num==num)
{
ptr->score=score;
break;
}
return head;
}
}
struct stud_node * max(struct stud_node * head)
{
struct stud_node maxp,ptr;
if(head==null)
return null;
else
{
maxp=head;
for(ptr=head->next;ptr!=null;ptr=ptr->next)
if(maxp->score<ptr->score)
maxp=ptr;
return maxp;
}
}
struct stud_node * min(struct stud_node * head)
{
struct stud_node minp,ptr;
if(head==null)
return null;
else
{
minp=head;
for(ptr=head->next;ptr!=null;ptr=ptr->next)
if(minp->score>ptr->score)
minp=ptr;
return minp;
}
}
void save(struct stud_node * head)
{
file fp;
if((fp=fopen("data.txt","w")) == null){ /打开文件（套用）*/
printf("file open error!\n");
exit(0);
}
struct stud_node * ptr;
if(head == null){
return;
}
for(ptr = head; ptr->next != null; ptr = ptr->next)
fprintf(fp,"%d %s %d\n", ptr->num, ptr->name, ptr->score);
fprintf(fp,"%d %s %d", ptr->num, ptr->name, ptr->score);/*输出的最后没有换行*/
if( fclose(fp) ){/*关闭文件（套用）*/
printf( "can not close the file!\n" );
exit(0);
}
}
struct stud_node read()
{
file fp;
if((fp=fopen("data.txt","r")) == null){
printf("file open error!\n");
exit(0);
}
struct stud_node * head,*tail,*p;
//int num,score;
//char name[20];
int size = sizeof(struct stud_node);
head = tail=null;
while(!feof(fp)){ /* 读到结束标志结束 */
p = (struct stud_node *) malloc(size);
fscanf(fp,"%d%s%d", &p->num, p->name, &p->score);
//head = insertdoc(head, p); /* 调用插入函数 */
p->next = null;
if(head == null)
head = p;
else
tail->next = p;
tail = p;
}
if( fclose(fp) ){
printf( "can not close the file!\n" );
exit(0);
}
return head;
}