Tips for golfing in PHP What general tips do you have for golfing in PHP? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to PHP (e.g. "remove comments" is not an answer). Please post one tip per answer.
Understand how variables and whitespace interact with PHP's language constructs.

In my (admittedly short) time golfing, I have found that PHP's language constructs (e.g. echo, return, for, while, etc) behave in a less-than-intuitive way when interacting with variables and whitespace.

echo$v;, for example, is perfectly valid, as are return$v; and other similar constructs. These small reductions in whitespace can lead to a significant cumulative decrease in length.

Keep in mind, though, that variables before language constructs require a space after, as in the following example:

foreach($a AS$b){}


Because AS is a language construct, a space is not required before the variable $b, but if one were to omit the space before it, resulting in $aAS, this would be parsed as a variable name and lead to a syntax error.