void receivef(char *fname)
     {FILE *fp;
      char ch;
      int count,temp,sum=0;
      remove(fname);
      if((fp=fopen(fname,"w"))==NULL)
         {printf("不能打开文件\n");
         exit(1);
         
         }
    printf("接收文件名:%s\n",fname);
    while(rport()!='?');
    sport('$');
    ch='.';
    sport(ch);
    temp=report();
    count=temp;
  rep:     
      for(;count;count--)
        {ch=rport();
         putc(ch,fp);
         sum=sum+ch;
      if(ferror(fp))
        {printf("写文件有误\n");
        exit(1);
        }
        }
   if(rport()!=sum)
      {ch='F';
      sport(ch);
      count=temp;
      sum=0;
      fseek(fp,-count,1);
      goto rep;
      }
   else 
        {ch='0';
         sport(ch);
          fclose(fp);
          printf("接收文件结束\n");
          }
          }