c +帮忙看一下定义的这个函数哪里不对

Question

void input(const char filename[])
{FILE *fp;
fp=fopen(filename,"r");
if(fp=NULL)
{printf("file not found!");
pressanykey();
return;
}
int i=0;
while(!feof(fp))
{fscanf(fp,"%s%*c%s%*c%s%*c%s%*c%d% %d %f %d%*c",books[i].booknum,books[i].name,books[i].publish,books[i].author,&books[i].date.y,&books[i].date.m,&books[i].price,&books[i].n);
i=i+1;
}
fclose(fp);
}

Answer 1

if(fp=NULL)
->
if(fp==NULL)

pressanykey();
这个在哪里定义的