php读取大文件最好的实现方法

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,'r')){         echo "打开文件失败，请检查文件路径是否正确，路径和文件名不要包含中文";         return false;     }     $pos=-2;     $eof="";     $str="";     while($n>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));

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($lines,0,$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, $pos, SEEK_END);
$t = fgetc($fp);
$pos --;
}
$t = " ";
$data .= fgets($fp);
$line --;
}
fclose ($fp);
echo $data