Question:

What will this code output and why?

$x = true and false;
var_dump($x);

Answer:

Surprisingly to many, the above code will output bool(true) seeming to imply that the and operator is behaving instead as an or.

The issue here is that the = operator takes precedence over the and operator in order of operations, so the statement $x = true and false ends up being functionally equivalent to:

$x = true;       // sets $x equal to true
true and false;  // results in false, but has no affect on anything

This is, incidentally, a great example of why using parentheses to clearly specify your intent is generally a good practice, in any language. For example, if the above statement $x = true and false were replaced with $x = (true and false), then $x would be set to false as expected.


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