php删除txt文件指定行及按行读取txt文档数据的方法

$keys = range(1,999);$file = fopen('key_11010000.txt',"w");foreach($keys as $key){  fwrite($file,"$key/r/n");}fclose($file);$f1 = fopen('key_11010000.txt','r');while(!feof($f1)){  $line=fgets($f1);  $line = trim($line);  $arr[] = $line;}$keys = array_filter($arr);var_dump($keys);

$f1 = fopen('key_11010000.txt','r');while(!feof($f1)){  $line=fgets($f1);  $line = trim($line);  $arr[] = $line;}$keys = array_filter($arr);var_dump($keys);die;