学生文件

文件读到链表中，对链表做相关操作，最后重写进文件中

typedef struct student{
     
 int num;
 char name[20];
 int score;
 struct student *next;
}stu;

stu *cre()
{
     
 stu*head = (stu*)malloc(sizeof(stu));
 head->next = NULL;
 return head;
}
stu* m = cre();//全局链表

stu *sort(stu*head){
            //冒泡排序

  stu*p = head;
  stu*q = head->next;
  stu*last = NULL;
  int temp;
  while (p != last)
  {
     
   while (q != last)
   {
     
    	if (p->num > q->num)
    	{
     
     		temp = p->num;
     		p->num = q->num;
     		q->num = temp;
    	}
   	 p = p->next;
   	 q = q->next;
   }
   last = p;
   p = head;  //重置p,q
   q = head->next;
  }
  return head;
}

void headinsert(stu *head)  //头插法
{
     
 stu *p = cre();
 printf("输入学号：\n");
 scanf("%d", &p->num);
 printf("输入姓名：\n");
 scanf("%s", p->name);
 printf("输入分数：\n");
 scanf("%d", &p->score);
 p->next = head->next;
 head->next = p;
}

stu *del(stu*head){
             //根据学号删除
 stu  *p, *q;// 带头节点的
 int n;
 printf("请输入要删除学生的学号：\n");
 scanf("%d", &n);
 q = head;
 p = q->next;
 while (p != NULL&&p->num != n){
     
  	q = p;
  	p = p->next;
 }
 if (p != NULL){
     
  	q->next = p->next;
  	free(p);
        printf("删除成功！\n");
 }
 else{
     
  printf("没有此人！\n");
 }
return head;
}

stu *revise(stu*head){
          //根据学号修改
 stu *p, *q;
 int n;
 q = head;
 p = q->next;
 printf("请输入要修改的学生的学号：\n");
 scanf("%d", &n);
 while (p != NULL&&p->num != n){
     
  	q = p;
 	p = p->next;
 }
 if (p != NULL){
     
  p->num = n;
  printf("输入姓名：\n");
  scanf("%s", p->name);
  printf("输入分数：\n");
  scanf("%d", &p->score);
  printf("修改成功！\n");
 }
 else
 {
     
  	printf("没有此人！\n");
 }
 return head;
}

stu *find(stu*head){
       //yes
 stu*p;
 int n;
 p = head;
 p = p->next;
 printf("请输入要查找的学生学号：\n");
 scanf("%d", &n);
 while (p&&p->num!=n){
     
  	p = p->next;
 }
 if (p)
 {
     
     printf("学号：%d\n", p->num);
     printf("姓名：%s\n", p->name);
     printf("分数：%d\n", p->score);
 }
 else 
     printf("没有此人！\n");
  return head;
}

void shuchu(stu*haed){
       //传指针 输出链表
 printf("全部数据：\n");
 stu *p;
 p = haed->next;
 printf("学号\t姓名\t分数\n");
 while (p != NULL)
 {
     
  printf("%d\t%s\t%d\n", p->num,p->name,p->score);
  p = p->next;
 }
}

void sa(stu*head){
          //文件
 FILE *fp;
 if((fp=fopen("abc.txt","w"))==NULL)  //只写方式
  {
        
        printf("cuowu打不开文件");
    	system("pause"); 
  } 
 stu *p;
 p = head->next;
 while (p != NULL)
 {
     
  	fprintf(fp,"%d %s %d\n",p->num,p->name,p->score);
  	p = p->next;
 }
 fclose(fp);
 }

void readfile(stu*in)//将文件的内容读出并且保存到链表中去
{
     
 FILE*fp;
 stu* infor;
 infor = (struct student*)malloc(sizeof(student)); 
 infor->name[20] = {
     0};
 infor->num = 0;
 infor->score = 0;
 infor->next = NULL;

if ((fp = fopen("abc.txt", "r")) == NULL)
 {
     
  	printf("cuowu打不开文件");
  	system("pause");
 }
 while (fscanf(fp,"%d %s %d\n",&infor->num,infor->name,&infor->score)!=EOF)
 {
       
  	insert(in,infor);
 }
 fclose(fp);
 printf("文件读取成功！(链表)\n");
}

int main(int argc, char** argv) {
     
int a = 0;
 readfile(m);
 while (1)
 {
     
  meau();
  printf("请输入命令：\n");
  scanf("%d",&a);
  switch (a)
  {
     
  case 1:sort(m);//排序
   	break;
  case 2:headinsert(m); //头插法
   	break;
  case 3:del(m); //删除
   	break;
  case 4:revise(m); //修改
  	break;
  case 5:find(m);  //查找
   	break;
  case 6:shuchu(m); //输出
   	break;
  case 7:sa(m);    //保存到文件，w形式打开
   	exit(0);
   	break;
  }
  	system("pause");
  	system("cls");
 }
 return 0;
 }

void meau()
{
     
 printf("1排序\n");
 printf("2添加\n");
 printf("3删除\n");
 printf("4修改\n");
 printf("5查找\n");
 printf("6输出\n");
 printf("7保存退出\n");//只写方式，文件存在会重写
}