PHP Short-circuit evaluation testing

<?php

function call_me($i) {
    echo 'called: '.$i."\n";
}

if(call_me(1) && false) {} // echo called: 1

if(false && call_me(2)) {}


if(true or call_me(3)) {}

if(call_me(4) or true) {} // echo called: 4


if(false && call_me(5) && true) {}



if(call_me(6) & false) {} // echo called: 6

if(false & call_me(7)) {} // echo called: 7


if(true | call_me(8)) {} // echo called: 8

if(call_me(9) | true) {} // echo called: 9

http://en.wikipedia.org/wiki/Short-circuit_evaluation

http://fr2.php.net/language.operators.logical

http://www.php.net/manual/en/language.operators.bitwise.php