Swap the values ​​of two variables without using a new variable

I often encounter this question during interviews, so I studied it specifically, as the question

$a = 1;

$b = 2;

Method 1:

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

Method 2:

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

Method 3: (If the variable is an integer)

$a=$a+$b; $b=$a-$b; $a=$a-$b;

The above introduces how to exchange the values ​​​​of two variables without new variables, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.