PHP's trim() function

Posted June 11th, 2009 in PHP

PHP's trim() function has a second parameter which allows a list of characters to trim to be passed in. This allows characters other than (or instead of) the default space character to be trimmed from a string. It works for trim(), rtrim() and ltrim().

The way trim() works is to remove whitespace from the start and end of the string passed in; rtrim() only does it to the end of the string (r = right) and ltrim() to the start of the string (l = left).

If you wanted to also trim off e.g. hypens and underscores then this can be passed in the character list as the second parameter like so:

$trimmed = trim($source, " -_");
$left_trimmed = ltrim($source, " -_");
$right_trimmed = rtrim($source, " -_");

In the above example, if $source was "_abc- " then $trimmed would be "abc".

I know this is pretty simple stuff, but often even when you've been programming in a particular language for several years you still may not be aware of all the parameters that can be passed to functions that can be real time savers.