2007.05.01
PHP Idiosyncrasies
Three reasons to make sure you know your programming language:
<?php
function test($code) {
$result = @eval("return ({$code});");
print ($result ? 'true ' : 'false ') . "$coden";
}
test( "gettype(key(array('s' => ''))) == 'string'" );
test( "gettype(key(array('1' => ''))) == 'string'" );
test( "'s' == 0" );
test( "0 == 's'" );
test( "$x == $x++" );
test( "(int)$x == $x++" );
function test($code) {
$result = @eval("return ({$code});");
print ($result ? 'true ' : 'false ') . "$coden";
}
test( "gettype(key(array('s' => ''))) == 'string'" );
test( "gettype(key(array('1' => ''))) == 'string'" );
test( "'s' == 0" );
test( "0 == 's'" );
test( "$x == $x++" );
test( "(int)$x == $x++" );
And here's the output:
true gettype(key(array('s' => ''))) == 'string'
false gettype(key(array('1' => ''))) == 'string'
true 's' == 0
true 0 == 's'
false $x == $x++
true (int)$x == $x++
false gettype(key(array('1' => ''))) == 'string'
true 's' == 0
true 0 == 's'
false $x == $x++
true (int)$x == $x++
In case you didn't catch what PHP is doing on the last pair, here's the equivalent processing in PHP code:
$y = &$x;
$x++;
($x == $y)
$x++;
($x == $y)
When casting $x with (int), PHP is no longer able to make use of the "let's just use a reference" over-optimization. Personally, I think it's a bug that the behaviour differs between the two.
Debuggers beware! ;)
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