Why is rtrim removing more characters, and giving weird output?

问题

I am trying to remove last few characters from the string using rtrim.

i have string "Scryed (download torrent) - TPB"

i want output string "Scryed"

e.g.

$title_t = "Scryed (download torrent) - TPB";

echo ($title_t)  ;
echo "\n";
$title =  ( rtrim ($title_t, "(download torrent) - TPB") );

echo ($title)  ;

gives

Scryed (download torrent) - TPB
Scry

Why is that ? expected output is

Scryed (download torrent) - TPB
Scryed

回答1:

It's because rtrim's second parameter is list of characters. Not a string to be trimmed! You should use a substr or str_replace:

$title =  substr($title_t, 0, strlen($title_t) - strlen("(download torrent) - TPB"));

or

$title = str_replace("(download torrent) - TPB", "" , $title_t);

来源：https://stackoverflow.com/questions/46307527/why-is-rtrim-removing-more-characters-and-giving-weird-output