#include<stdio.h>
#include<malloc.h>
struct student
{
    int num;
    char name;
    int age;
    int sex;
    struct student *link;
}stud;
  
 creat(int n)
{
    struct student *h,*p;
    int i;
    h=(struct student *)malloc(sizeof(stud));
    if(h==NULL)
    {
        printf("not enough memory!");
        return(0);
    }
    h=NULL;
    for(i=0;i<=n;i++)
    {
         
         
        if((p=(struct student *)malloc(sizeof(stud)))==NULL)

            
            
        {
            printf("内存不足！");
            return(0);
        }
        scanf("%d",&p->num);
        scanf("%s",&p->name);
        scanf("%d",&p->age);
        scanf("%s",&p->sex);
        p->link=h;
        h=p;
    }
     void save(stud *h)
     {
        FILE *fP;
        stud *p;
        if((fp=fopen("d:\\123","w"))==NULL)
        {
            printf("can now open file!");
            exit(1);
        }
        printf("\n saving file...\n");
        p=h;
        while(p!=NULL)
        {
            fwrite(p,sizeof(stud),1,fp);
            p=p->next;
        }
        fclose(fp);
        printf("*******save successful!********\n");
   
   
   
    }
 }
    void main()
    {
        struct student *h;
   
        h=(struct student *)creat(4);
         save(h);
    }
   

更正一下
#include<stdio.h>
#include<malloc.h>
struct student
{
    int num;
    char name;
    int age;
    int sex;
    struct student *link;
}stud;
  
 creat(int n)
{
    struct student *h,*p;
    int i;
    h=(struct student *)malloc(sizeof(stud));
    if(h==NULL)
    {
        printf("not enough memory!");
        return(0);
    }
    h=NULL;
    for(i=0;i<=n;i++)
    {
         
         
        if((p=(struct student *)malloc(sizeof(stud)))==NULL)

            
            
        {
            printf("内存不足！");
            return(0);
        }
        scanf("%d",&p->num);
        scanf("%s",&p->name);
        scanf("%d",&p->age);
        scanf("%s",&p->sex);
        p->link=h;
        h=p;
    }
     void save(struct student *h)
     {
        FILE *fp;
        stud *p;
        if((fp=fopen("d:\\123","w"))==NULL)
        {
            printf("can now open file!");
            exit(1);
        }
        printf("\n saving file...\n");
        p=h;
        while(p!=NULL)
        {
            fwrite(p,sizeof(stud),1,fp);
            p=p->link;
        }
        fclose(fp);
        printf("*******save successful!********\n");
   
     
   
    }
 }
    void main()
    {
        struct student *h;
   
        h=(struct student *)creat(4);
        save(h);
    }
   

好像前两天有人帖这个代码，你们都是一个老师教的吗？犯的错误都一样

creat(int n)
{
    struct student *h,*p;
    int i;
    h=(struct student *)malloc(sizeof(stud));
    if(h==NULL)
    {
        printf("not enough memory!");
        return(0);
    }
    h=NULL;//有致空，那上面请求内存有必要有吗？

没呀，不知道。

我是写作两句了，这个没错

void main()
    {
        struct student *h;
   
        h=(struct student *)creat(4);// 你的creat函数返回值是指针吗？检查一下
        save(h);
    }

强制转换为指针变量了

  
creat(int n)
{
    struct student *h,*p;
    int i;
    h=(struct student *)malloc(sizeof(stud));
    if(h==NULL)
    {
        printf("not enough memory!");
        return(0);
    }
    h=NULL;
申请完内存再置空，有意义吗？？？？？？

我的天哪，根本就不是指针类型就能转换成结构体指针？？？谁教给你的，int也能强制转换成指针吗？？？