从键盘输入一批学生的数据，然后把…

#include<stdio.h>
#include<stdlib.h>
struct student
{
 int num;
 char name[20];
 char sex;
 int age;
 float score;
}
main()
{
 struct student stud;
 char numstr[20],ch;
 FILE *fp;
 if((fp=fopen("stud.dat","wb")==NULL))
 {
  printf("can't open filestud,dat\n");
  exit(1);
 }
 do
 {
  printf("enternumber:");gets(numstr);stud.num=atoi(numstr);
  printf("entername:");gets(stud.name);
  printf("entersex:");stud.sex=getchar();getchar();
  printf("enterage:");gets(numstr);stud.age=atoi(numstr);
  printf("enterscore:");gets(numstr);stud.score=atof(numstr);
  fwrite(&stud,sizeof(structstudent),1,fp);//将结构变量stud的值写入文件
  printf("have another studentrecord(y/n)?");
  ch=getchar();getchar();
 }
 while(ch=='Y'||ch=='y');
 fclose(fp);
}