little trouble with OR operator

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'.

Why are you using `===` and `!==` (instead of `==` and `!=`)? Also, `$num_rows` is probably an int so you should just be using `$num_rows == 0`. — Matt Browne, Aug 25 '14 at 14:07
...plus `$_GET` will always supply a _string_, while userID sounds like it might be an integer value, so `===` will fail. — Michael Berkowski, Aug 25 '14 at 14:07

score 2 · Answer 1 · edited May 23 '17 at 12:13

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

score 1 · Answer 2 · answered Aug 25 '14 at 14:07

1

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

answered Aug 25 '14 at 14:07

Mihai

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score 1 · Answer 3 · answered Aug 25 '14 at 14:07

1

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

answered Aug 25 '14 at 14:07

Rahul Tripathi

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score 0 · Answer 4 · answered Aug 25 '14 at 14:14

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';
}

score 0 · Answer 5 · answered Aug 25 '14 at 15:58

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. :)

little trouble with OR operator

5 Answers5