#include <stdio.h>
#include<dos.h>
#include<stdlib.h>
#include<string.h>
#include<mem.h>
#include<ctype.h>
#include<alloc.h>
#define LEN sizeof(STUDENT)
typedef struct stu
{char num[6]
char name[5]
int score[3]
int sum
float average
int order
struct stu *next
}STUDENT
STUDENT *init()
int menu_select()
STUDENT *create()
void print(STUDENT *head)
void search(STUDENT *head)
STUDENT *delete(STUDENT *head)
STUDENT *sort(STUDENT *head)
STUDENT *insert(STUDENT *head,STUDENT *new)
void save(STUDENT *head)
STUDENT *load()
main()
{STUDENT *head,new
head=init()
for()
{switch(menu_select())
{
case 1:head=create()break
case 2:print(head)break
case 3:search(head)break
case 4:head=delete(head)break
case 5:head=sort(head)break
case 6:head=insert(head,&new)break
case 7:save(head)break
case 8:head=load()break
case 9:exit(0)
}
}
}
STUDENT *init()
{
return NULL
}
menu_select()
{int n
struct date d
getdate(&d)
printf("n按任一键进入主菜单...... npress any key to enter the menu......")
getch()
clrscr()
printf("********************************************************************************n")
printf("tt 欢迎 Welcome ton")
printf("nttt 使用学生管理系统1.0nnttttt-----------景炎中学计算机组WJQn")
printf("*************************************MENU***************************************n")
printf("ttt1. 输入学生成绩记录 Enter the recordn")
printf("ttt2. 显示 Print the recordn")
printf("ttt3. 寻找 Search record on namen")
printf("ttt4. 删除 Delete a recordn")
printf("ttt5. 排序 Sort to make new a filen")
printf("ttt6. 插入 Insert record to listn")
printf("ttt7. 保存 Save the filen")
printf("ttt8. 读取 Load the filen")
printf("ttt9. 退出 Quitn")
printf("ntt 制作吴俊遒WJQ Made by Wu Junqiu.n")
printf("********************************************************************************n")
printf("tttt当前系统日期:%d%d%dn",d.da_year,d.da_mon,d.da_day)
do{
printf("nttt输入你的选择Enter your choice(1~9):")
scanf("%d",&n)
}while(n<1||n>9)
return(n)
}
STUDENT *create()
{int i,s
STUDENT *head=NULL,*p
clrscr()
for()
{p=(STUDENT *)malloc(LEN)
if(!p)
{printf("n输出内存溢出. Out of memory.")
return (head)
}
printf("输入学号Enter the num(0:list end):")
scanf("%s",p->num)
if(p->num[0]=='0') break
printf("输入名字Enter the name:")
scanf("%s",p->name)
printf("请输入3门成绩Please enter the %d scoresn",3)
s=0
for(i=0i<3i++)
{
do{
printf("成绩score%d:",i+1)
scanf("%d",&p->score[i])
if(p->score[i]<0 || p->score[i]>100)
printf("数据错误,请重新输入 Data error,please enter again.n")
}while(p->score[i]<0 || p->score[i]>100)
s=s+p->score[i]
}
p->sum=s
p->average=(float)s/3
p->order=0
p->next=head
head=p
}
return(head)
}
void print(STUDENT *head)
{int i=0
STUDENT *p
clrscr()
p=head
printf("n************************************STUDENT************************************n")
printf("-------------------------------------------------------------------------------n")
printf("| Rec | Num | Name | Sc1 | Sc2 | Sc3 | Sum | Ave | Order |n")
printf("-------------------------------------------------------------------------------n")
while(p!=NULL)
{
i++
printf("| %3d | %4s | %-4s | %3d | %3d | %3d | %3d | %4.2f | %-5d|n",
i, p->num,p->name,p->score[0],p->score[1],p->score[2],p->sum,p->average,p->order)
p=p->next
}
printf("-------------------------------------------------------------------------------n")
printf("**************************************END**************************************n")
}
void search(STUDENT *head)
{STUDENT *p
char s[5]
clrscr()
printf("请输入个姓名来查找. Please enter name for searching.n")
scanf("%s",s)
p=head
while(strcmp(p->name,s) &&p != NULL)
p=p->next
if(p!=NULL)
{printf("n*************************************FOUND************************************n")
printf("-------------------------------------------------------------------------------n")
printf("| Num | Name | sc1 | sc2 | sc3 | Sum | Ave | Order |n")
printf("-------------------------------------------------------------------------------n")
printf("| %4s | %4s | %3d | %3d | %3d | %3d | %4.2f | %-5d|n",
p->num,p->name,p->score[0],p->score[1],p->score[2],p->sum,p->average,p->order)
printf("-------------------------------------------------------------------------------n")
printf("***************************************END**************************************n")
}
else
printf("n没有该学生 There is no num %s student on the list.n",s)
}
STUDENT *delete(STUDENT *head)
{int n
STUDENT *p1,*p2
char c,s[6]
clrscr()
printf("请输入要删除的学号 Please enter the deleted num: ")
scanf("%s",s)
p1=p2=head
while(strcmp(p1->num,s) &&p1 != NULL)
{p2=p1
p1=p1->next
}
if(strcmp(p1->num,s)==0)
{printf("**************************************FOUND************************************n")
printf("-------------------------------------------------------------------------------n")
printf("| Num | Name | sc1 | sc2 | sc3 | Sum | Ave | Order |n")
printf("-------------------------------------------------------------------------------n")
printf("| %4s | %4s | %3d | %3d | %3d | %3d | %4.2f | %-5d|n",
p1->num,p1->name,p1->score[0],p1->score[1],p1->score[2],p1->sum,p1->average,p1->order)
printf("-------------------------------------------------------------------------------n")
printf("***************************************END**************************************n")
printf("n是否要删除,输入Y删除,N则退出nAre you sure to delete the student Y/N ?")
for()
{scanf("%c",&c)
if(c=='n'||c=='N') break
if(c=='y'||c=='Y')
{
if(p1==head)
head=p1->next
else
p2->next=p1->next
n=n-1
printf("n学号为(Num): %s 学生以被删除(student have been deleted.)n",s)
printf("别忘了保存. Don't forget to save.n")break
}
}
}
else
printf("n没有这个学生在表上nThere is no num %s student on the list.n",s)
return(head)
}
STUDENT *sort(STUDENT *head)
{int i=0
STUDENT *p1,*p2,*t,*temp
temp=head->next
head->next=NULL
while(temp!=NULL)
{
t=temp
temp=temp->next
p1=head
p2=head
while(t->average<p1->average&&p1!=NULL)
{
p2=p1
p1=p1->next
}
if(p1==p2)
{
t->next=p1
head=t
}
else
{
t->next=p1
p2->next=t
}
}
p1=head
while(p1!=NULL)
{
i++
p1->order=i
p1=p1->next
}
printf("排序成功 Sorting is sucessful.n")
return (head)
}
STUDENT *insert(STUDENT *head,STUDENT *new)
{STUDENT *p0,*p1,*p2
int n,sum1,i
p1=head
p0=new
printf("nPlease enter a new record.n")
printf("输入学号Enter the num:")
scanf("%s",new->num)
printf("输入名字Enter the name:")
scanf("%s",new->name)
printf("Please enter the %d scores.n",3)
sum1=0
for(i=0i<3i++)
{
do{
printf("成绩score%d:",i+1)
scanf("%d",&new->score[i])
if(new->score[i]>100||new->score[i]<0)
printf("数据错误Data error,please enter again.n")
}while(new->score[i]>100||new->score[i]<0)
sum1=sum1+new->score[i]
}
new->sum=sum1
new->average=(float)sum1/3
new->order=0
if(head==NULL)
{head=p0p0->next=NULL}
else
{while((p0->average<p1->average)&&(p1->next!=NULL))
{p2=p1
p1=p1->next
}
if(p0->average>=p1->average)
{if(head==p1)head=p0
else p2->next=p0
p0->next=p1}
else
{p1->next=p0p0->next=NULL}
}
n=n+1
head=sort(head)
printf("n学生Student %s 已被更新have been inserted.n",new->name)
printf("不要忘了保存Don't forget to save the new file.n")
return(head)
}
void save(STUDENT *head)
{FILE *fp
STUDENT *p
char outfile[10]
printf("输出文件例如:c:score Enter outfile name,for example c:scoren")
scanf("%s",outfile)
if((fp=fopen(outfile,"w"))==NULL)
{
printf("打不开文件Cannot open the filen")
return
}
printf("n保存中...Saving the file......n")
p=head
while(p!=NULL)
{
fwrite(p,LEN,1,fp)
p=p->next
}
fclose(fp)
printf("保存成功....Save the file successfully!n")
}
STUDENT *load()
{STUDENT *p1,*p2,*head=NULL
FILE *fp
char infile[10]
printf("倒入文件例如:c:score Enter infile name,for example c:scoren")
scanf("%s",infile)
if((fp=fopen(infile,"r"))==NULL)
{
printf("打不开文件Can not open the file.n")
return(head)
}
printf("n寻找文件...Loading the file!n")
p1=(STUDENT *)malloc(LEN)
if(!p1)
{
printf("内存溢出!Out of memory!n")
return(head)
}
head=p1
while(!feof(fp))
{
if(fread(p1,LEN,1,fp)!=1) break
p1->next=(STUDENT *)malloc(LEN)
if(!p1->next)
{
printf("Out of memory!n")
return (head)
}
p2=p1
p1=p1->next
}
p2->next=NULL
fclose(fp)
printf("n你成功的从文件中读取了数据!nYou have success to read data from the file!n")
return (head)
}
p3=head->next
while(p3->num!=p1->num) //这里应该是判断是否到结尾 while(p3!=NULL)
{
if(p1->num==p3->num)
{
hh=1
break
}else hh=0
p3=p3->next
}
假设学生数未知，但不超过10000。
如果用普通数组，那么你不得不在程序一开始就声明一个长度为10000的数组，就算最终录入的学生只有5个人，但是还是会占用10000个单位的空间。
而用链表，程序一开始甚至一个空间都不需要，当要输入一个学生时，才现声明一个单位空间。如果最终只录入了7人，那么就只占了7个单位空间。
动态内存所说的节约空间，只是相对于固定分配的普通数组而言。
而你说的文件与内存的问题，跟链表无直接关系。不管你用什么数据结构，当数据太多，超过内存容量的时候，肯定都是不能同时全部读入内存的，都必须把当前不需要的部分暂存在硬盘上，等内存把当前数据处理完，写回文件，再把其他部分读入内存操作。
任何数据，都可以有两种存在状态：内存中和硬盘上。所以一个结构体可以全部存在于内存中，也可以在硬盘上。只要内存容量足够，无论多少结构体都可以存在于内存中。而在C语言里，大多数情况下，“结构体”都是在内存中的，因为当“结构体”写回硬盘后，一般都不在称之为“结构体”，而是一堆数据。
C语言的所有数据结构都是指活跃在内存中的数据的结构，因为某个特定结构的数据都是可以直接操作的，这只有放在内存中才能实现。
排序的问题，一般来讲，确实是所有学生都要读入内存才能进行排序。
记住一点，任何数据的操作都是在内存中进行的。
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