Is there a PHP function for swapping the values of two variables?

Question

Say for instance I have ...

$var1 = ABC
$var2 = 123

and under certain conditions I want to swap the two around like so...

$var1 = 123
$var2 = ABC

Is there a PHP function for doing this rather than having to create a 3rd variable to hold one of the values then redefining each, like so...

$var3 = $var1
$var1 = $var2
$var2 = $var3

For such a simple task its probably quicker using a 3rd variable anyway and I could always create my own function if I really really wanted to. Just wondered if something like that existed?

Answer 1

There's no function I know of, but there is a one-liner courtesy of Pete Graham:

list($a,$b) = array($b,$a);

not sure whether I like this from a maintenance perspective, though, as it's not really intuitive to understand.

Also, as @Paul Dixon points out, it is not very efficient, and is costlier than using a temporary variable. Possibly of note in a very big loop.

However, a situation where this is necessary smells a bit wrong to me, anyway. If you want to discuss it: What do you need this for?

Answer 2

list($var1,$var2) = array($var2,$var1);

Answer 3

Yes, try this:

// Test variables
$a = "content a";
$b = "content b";

// Swap $a and $b
list($a, $b) = array($b, $a);

This reminds me of python, where syntax like this is perfectly valid:

a, b = b, a

It's a shame you can't just do the above in PHP...