Remove a part of a string, but only when it is at the end of the string

Question

I need to remove a substring of a string, but only when it is at the END of the string.

for example, removing \'string\' at the end of the following strings :

Answer 1

You'll note the use of the $ character, which denotes the end of a string:

$new_str = preg_replace('/string$/', '', $str);

If the string is a user supplied variable, it is a good idea to run it through preg_quote first:

$remove = $_GET['remove']; // or whatever the case may be
$new_str = preg_replace('/'. preg_quote($remove, '/') . '$/', '', $str);

Answer 2

You can use rtrim().

php > echo rtrim('this is a test string', 'string');
this is a test 

This will work only in some cases, as 'string' is just a characters mask and char order will not be respected.

Answer 3

preg_replace and this pattern : /string\z/i

\z means end of the string

http://tr.php.net/preg_replace

Answer 4

IF you don't mind about performance AND the part of the string could be placed only at the end of string, THEN you can do this:

$string = "this is a test string";
$part = "string";
$string = implode( $part, array_slice( explode( $part, $string ), 0, -1 ) );
echo $string;
// OUTPUT: "this is a test "

Answer 5

Using regexp may fails if the substring has special characters.

The following will work with any strings:

$substring = 'string';
$str = "this string is a test string";
if (substr($str,-strlen($substring))===$substring) $str = substr($str, 0, strlen($str)-strlen($substring));

Answer 6

I suppose you could use a regular expression, which would match string and, then, end of string, coupled with the preg_replace() function.

Something like this should work just fine :

$str = "this is a test string";
$new_str = preg_replace('/string$/', '', $str);

Notes :

• string matches... well... string
• and $ means end of string

For more informations, you can read the Pattern Syntax section of the PHP manual.