PHP references allow you to make two variables to refer to the same content. Meaning, when you do:
$bpoint to the same content.
$bare completely equal here, that's not
$ais pointing to
$bor vice versa, that's
$bpointing to the same place.
Note: If array with references is copied, its values are not dereferenced. This is valid also for arrays passed by value to functions.
Note: If you assign, pass or return an undefined variable by reference, it will get created.
The same syntax can be used with functions, that return references, and with new operator (in PHP 4.0.4 and later):new return reference automatically so using =& in this context is deprecated and produces E_STRICT level message.
Note: Not using the & operator causes a copy of the object to be made. If you use $this in the class it will operate on the current instance of the class. The assignment without & will copy the instance (i.e. the object) and $this will operate on the copy, which is not always what is desired. Usually you want to have a single instance to work with, due to performance and memory consumption issues.
While you can use the @ operator to mute any errors in the constructor when using it as @new, this does not work when using the &new statement. This is a limitation of the Zend Engine and will therefore result in a parser error.
If you assign a reference to a variable declared global
inside a function, the reference will be visible only inside the function.
You can avoid this by using the
Note: If you assign a value to a variable with references in a foreach statement, the references are modified too.
The second thing references do is to pass variables by-reference. This is done by making a local variable in a function and a variable in the calling scope reference to the same content. Example:
$ato be 6. This happens because in the function
$varrefers to the same content as
$a. See also more detailed explanations about passing by reference.
The third thing reference can do is return by reference.