PHP quirks and pitfalls [closed]

Answer 1

Serializing objects that process XML structures and then unserializing them does not restore the original XML structure:

$dom = new DOMDocument;
$dom->loadXML('<test/>');

$dom = serialize($dom);
$dom = unserialize($dom);

var_dump($dom->saveXML());
// $ Warning: DOMDocument::saveXML(): Couldn't fetch DOMDocument in ...
// $ NULL

Similarly for SimpleXML objects.

Answer 2

Multiple ways of doing truth tests (not operator, empty(), is_null(), isset()) + weak typing = this

With some discipline you can mostly avoid the need to refer to this table:

• For general truth tests, you can use boolean comparison if ($) { ... } if (!$x) { ... }. It behaves the way boolean operators in most languages do.

• Always use empty() if you want to test form input for falsy values (it treats "0" as false).

• Always use isset() if you want to determine whethere a variable is set or not

• Use is_null() or $x === NULL if you only need to check for NULL

Answer 3

Inconsistent naming conventions of built-in functions. For example this set of string processing functions:

 str_shuffle()
 str_split()
 str_word_count()
 strcasecmp()
 strchr()
 strcmp()

Solution: Leave the manual open at all times.

Answer 4

Sometimes you like to pass a function-result to another function directly, which only accepts variables as input.

For example:

array_pop(  explode('\\', get_class($this))  )

…will result in an E_STRICT-error "Only variables should be passed by reference". To get get it working just add another pair of brackets around the inner (returned) statement:

array_pop( (explode('\\', get_class($this))) )

(If your are using namespaces and extended classes, this line returns only the class name (without namespace) from the calling object–not the parent-class which was extended and may hold this function.)

Answer 5

Integer size is platform dependent. You can't normally use 64bit integers on a 32bit machine without any outside module. Additionally, you cannot declare unsigned integers.

Answer 6

Some newly introduced PHP features fall flat because there's no guarantee they'll be supported by default in hosting environments.

The biggest peeve of mine is the short_tags setting that enables <? foobar(); ?> and <?=$var ?> tag syntax. I argue PHP should've enabled this feature by default, rather than opt-in.

== EDIT ==

In PHP >= 5.4 the short_tags setting is no longer taken into consideration for the shorthand echo statement , as such it will be available in every hosting environment that supports PHP 5.4 and up.