little trouble with OR operator - php

Question

i got into some trouble by using OR if one condition is true and the other false.
in my constillation right now it is always only the second condition token.
if($num_rows === '0' OR $_GET['id'] !== $_SESSION['UserID'])
{ echo "show me something"; }
else
{ show nothing; }
i get only always 'show nothing'.

Answer 1

Note that === is strict comparison. I think the following:
$num_rows === '0'
should rather be:
$num_rows == 0
$num_rows is presumably an integer and not a string (a piece of text).
Related: PHP == vs === on Stack Overflow
Watch out with the second comparison, too:
$_GET['id'] !== $_SESSION['UserID']
Here, it's probably better to use != in favor of !== as well. $_GET is generally read as string, so even something like ?id=5 will return as string "5" and not as integer 5
Here's a quick test to illustrate:
if (isset($_GET['id'])) {
echo '<h2>Comparison with == 5</h2>';
var_dump( ($_GET['id'] == 5) );
echo '<h2>Comparison with == "5"</h2>';
var_dump( ($_GET['id'] == "5") );
echo '<h2>Comparison with === 5</h2>';
var_dump( ($_GET['id'] === 5) );
echo '<h2>Comparison with === "5"</h2>';
var_dump( ($_GET['id'] === "5") );
}
else {
echo 'Please set an ?id to test';
}
This will output (notice the third item is false) the following with ?id=5:
Comparison with == 5
boolean true
Comparison with == "5"
boolean true
Comparison with === 5
boolean false
Comparison with === "5"
boolean true

Answer 2

Probably because you use absolute equality with a string.Mysli_num_rows returns an int.
http://php.net/manual/en/language.operators.comparison.php
Equal and of the same type

Answer 3

You dont need to use === as it is a strict comparison and $num_rows is probably an int Try this:-
if($num_rows == 0 OR $_GET['id'] != $_SESSION['UserID'])
$_GET['id'] will provide you a string. You may chech the manual for details

Answer 4

To be really correct, need something like this:
if ($num_rows === FALSE) {
echo 'db resource/link gone';
}
elseif ($num_rows === 0 || intval($_GET['id']) !== intval($_SESSION['UserID'])) {
echo 'no db result or id mismatch';
}
elseif (intval($num_rows) > 0 && intval($_GET['id']) === intval($_SESSION['UserID'])) {
echo 'everything good';
}
else {
echo 'something unhandled went wrong';
}

Answer 5

thanks for all the answers. i got it to work. i change the order and the opreator to what you've suggested.
i made it like this:
if($num_rows > 0 OR $_GET['id'] == $_SESSION['UserID']) { echo "show nothing"; }
else { show me some stuff }
so thanks again for all the help. :)