学生成绩档案管理系统.

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

struct student              //定义一个结构体，存放的是学生成绩档案
{
 int num;
 char name[12];
 float score;
 struct student *next;
};

typedef struct student STU;           //声明STU代表struct student

struct student *create(void)          //创建学生成绩档案函数
{
 struct student *head, *tail, *p;                                //head头指针，tail尾指针。                  
 
 int num;
 char name[12];
 float score;
 
 head = tail = NULL;

 printf("please input num\n");
 scanf("%d", &num);            //输入学号
 
 while(num != 0)                                             
 {
  printf("please input: name score\n");
  scanf("%s %f", name, &score);        //输入姓名，成绩
  
  p = (struct student *)malloc(sizeof(struct student));       //给结构体指针p分配空间
  
  p->num = num;                                             //把数据送进结构体
  strcpy(p->name, name);
  p->score=score;
  
  p->next = NULL;

  if(head == NULL)
  {
   head = tail = p;
  }
  else
  {
   tail->next=p;           //tail指针随着p后移
   tail=p;
  }
  printf("please input a num\n");
  scanf("%d", &num); 
 }
  return head;
}

struct student *readfp(void)                                       //从文件读入
{
 struct student *head, *tail, *p, new;
 
 int num;
 char name[12];
 float score;
 
 head = tail = NULL;
 FILE *fp;
 fp = fopen("save.dat","r");
 
 fread(&new, sizeof(STU),1, fp);

 while(!feof(fp))                                              //判断文件是否处于文件结束位置，如文件结束，则返回值为1，否则为0。一般当该函数返回值为1时，结束对文件的读取操作
 {
  p = (struct student *)malloc(sizeof(struct student));
  
  p->num = new.num;
  strcpy(p->name, new.name);
  p->score= new.score; 
  
  p->next = NULL;
  
  if(head == NULL)
  { 
   head = tail = p;
  }
  else
  {
   tail->next=p; 
   tail=p;
  }

  fread(&new, sizeof(STU),1, fp);

  }
  return head;
}

show(struct student *head)           //显示学生的档案
{
 struct student *p;
 p = head;
 while(p!=NULL)
 {
  printf("num=%d, name=%s, score=%f\n", p->num, p->name, p->score);
  p = p->next;
 }
}

struct student* insert(struct student *head)                     //插入学生的档案
{
 struct student *new1, *p, *q;
 
 int num;
 char name[12];
 float score;
 
 p = head;
 
 new1 = (struct student *)malloc(sizeof(struct student));

 printf("please input a num\n");
 scanf("%d", &new1->num);
 printf("please input: name score\n");
 scanf("%s %f", new1->name, &new1->score);                  //输入新学生的档案        
 
 if(p == NULL)
 {
  head = new1;
  new1->next=NULL; 
 }
 else
 {
  while(p->num <new1->num && p->next!=NULL)              //P指向的档案编号小于要插入的学生档案的编号时，p向后移动一位
  {
   q=p;
   p=p->next;
  }
  if(p->num >= new1->num)
  {
   if(p == head)
   {
    head=new1;
    new1->next=p;
   }
   else                                              //此时要插入的档案的位置在q和p之间
   {
    q->next=new1;
    new1->next=p;
   }
  }
  else                                                  //要插入的学生档案编号比已有编号都大，因此放在最后面
  {
   p->next = new1;
   new1->next = NULL;
  }
 }
 return head;
}

struct student *delete(struct student *head)                  //删除一条学生档案信息
{
 struct student *p, *q;
 int num;
 p=head;
 
 printf("please input data to delete\n");
 scanf("%d", &num);
 //while(p->data!=x && p!=NULL )
 
 while(p != NULL && p->num != num )
 {
  q=p;
  p=p->next;
 }
 if(p==NULL)
 {
  printf("have not the data\n");
 }
 else
 {
  if(p==head)
  {
   head=p->next; 
   free(p);
  }
  else
  {
   q->next=p->next;
   free(p); 
  }
 }
 return head; 
}

void save(STU *head)                                           //将学生档案保存到文件中
{
 FILE *fp;
 STU *p;
 fp=fopen("save.dat", "w");
 p = head;
 while(p != NULL)
 {
  fwrite(p, sizeof(STU), 1, fp);
  p=p->next;
 }
 fclose(fp);
}

int main()
{
 STU *head=NULL;
 int x;
 while(1)
 {
 printf("|-----Menu-------|\n");
 printf("|--1: Create-----|\n");
 printf("|--2: insert-----|\n");
 printf("|--3: delete-----|\n");
 printf("|--4: save  -----|\n");
 printf("|--5: show ------|\n");
 printf("|--6: readfp-----|\n");
 printf("|--0: exit  -----|\n");
 printf("please input choice\n");
 scanf("%d", &x);
 switch(x)
 {
  case 1:
   head = create();
   break;
  case 2:
   head = insert(head);
   break;
  case 3:
   head = delete(head);
   break;
  case 4:
   save(head);
   break;
  case 5:
   show(head);
   break;
  case 6:
   head = readfp();
   break;
  case 0:
   printf("bye bye\n");
   return 0;
  default :
   printf("invaild choice\n");
   break;
 }
  getchar();
 }
}