Is it safe to use xor for variable swapping in PHP

Is it safe to use this kind of variable swapp开发者_开发技巧ing in php ?

$a^=$b^=$a^=$b;

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No, because the variables may not be types that can be XORd the way you expect. The PHP idiom for swapping two variables (of any scalar type) in one line is:

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

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Only correct when both are integer. It's readability is poor,and efficiency is not good too,why use it?