读定txt文件的有关问题

$handle  =  fopen ( 'a.txt' ,  'r+' );
rewind($handle);
fwrite($handle,"这是第一行\r\n");
fclose ( $handle );

$handle  =  fopen ( 'a.txt' ,  'r+' );
$arr=array();
while($line=fgets($handle)){
    $arr[]=$line;
}
fclose ( $handle );
echo end($arr);