[单选]  voidxw1(char*fname){          FILE*fout=fopen(fname,“w“);          chara[20];          printf(“每个字符串长度小于20，字符串end作为结束标志“);          while(1){              scanf(“%s“,a);              if(strcmp(a,“end“)==0)break;              fputs(a,fout);              fputc('',fout);          }          fclose(fout);      }