php实现读取超大文件的方法

0){ while($eof != "n"){ if(!fseek($fp,$pos,SEEK_END)){ $eof = fgetc($fp); $pos–; }else{ break; } } $str .= fgets($fp); $eof = ""; $n–; } return $str; }

echo nl2br(FileLastLines('sss.txt',4));
/**

• • • 取文件最后$n行 *
• @param string $filename 文件路径 *
• @param int $n 最后几行 *
• @return mixed false表示有错误，成功则返回字符串
  */
  function FileLastLines($filename,$n){
  if(!$fp = fopen($filename,SEEK_END)){
  $eof = fgetc($fp);
  $pos--;
  }else{
  break;
  }
  }
  $str .= fgets($fp);
  $eof = "";
  $n--;
  }
  return $str;
  }
  echo nl2br(FileLastLines('sss . txt',4));

function tail($fp,$n,$base = 5)
{
assert($n > 0);
$pos = $n + 1;
$lines = array();
while(count($lines) < = $n){
try{
fseek($fp,- $pos,SEEK_END);
}
catch (Exception $e){
fseek(0);
break;
}
$pos *= $base;
while(!feof($fp)){
array_unshift($lines,fgets($fp));
}
}
return array_slice($lines,$n);
}
var_dump(tail(fopen("access.log","r+"),10));
$fp = fopen($file,"r");
$line = 10;
$pos = -2;
$t = " ";
$data = "";
while ($line > 0){
while ($t != "n"){
fseek($fp,SEEK_END);
$t = fgetc($fp);
$pos --;
}
$t = " ";
$data .= fgets($fp);
$line --;
}
fclose ($fp);
echo $data;
?>