Newbie question: Why is my PHP OR operator not working? - php

Question

I have a function where I want to display something if the value equals A, C or D.
The problem is if the value is set at B or E, the function is display data in the A.C.D. set in addition to the B or E set.
What am I doing wrong?
$linkp = opensky_featured_image_position();
if ( $linkp == 'featuredimg-1' || 'featuredimg-3' || 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
if ( $linkp == 'featuredimg-2' ) {
echo '<h1>L - '. opensky_featured_image_position() .'</h1>';
}
if ( $linkp == 'featuredimg-5' ) {
echo '<h1>N - '. opensky_featured_image_position() .'</h1>';
}

Answer 1

if ( $linkp == 'featuredimg-1' || 'featuredimg-3' || 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
Should be
if ( $linkp == 'featuredimg-1' || $linkp == 'featuredimg-3' || $linkp == 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
If all the values of $linkkp are defined you could do something like this
$linkArr = array(
'featuredimg-1' => 'F',
'featuredimg-2' => 'L',
'featuredimg-3' => 'F',
'featuredimg-4' => 'F',
'featuredimg-5' => 'N',
);
$linkp = opensky_featured_image_position();
echo '<h1>'.$linkArr[$linkp].' - '. opensky_featured_image_position() .'</h1>';

Answer 2

It's all about operator precedence. Since == is with higher precedence, your code is rewritten as follows:
if ( ($linkp == 'featuredimg-1') || 'featuredimg-3' || 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
which turns to be
if ( false || true || true ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
Since when you cast a non-empty string to bool, it will be evaluated as true.
You have to rewrite it:
if ( $linkp == 'featuredimg-1' || $linkp == 'featuredimg-3' || $linkp == 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
Which is equalent to:
if ( ($linkp == 'featuredimg-1') || ($linkp == 'featuredimg-3') || ($linkp == 'featuredimg-4') ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
But when you are dealing with such condition, maybe it's better to use in_array

Answer 3

For me this looks like that you're making too much use of if to describe something very simple: Certain values map to characters, that is essentially static data. No need to use so much verbose code to write that data into your code.
Consider using arrays instead to get the character you're actually looking for based on the number and then just echo it afterwards:
$linkp = opensky_featured_image_position();
sscanf($linkp, 'featuredimg-%d', $number);
$chars = 'FLN';
$map = array(1 => 0, 2 => 1, 3 => 0, 4 => 0, 5 => 2);
echo '<h1>', $chars[$map[$number]], ' - ', $linkp, '</h1>';
Demo

Answer 4

It should be:
if ( $linkp == 'featuredimg-1' || $linkp == 'featuredimg-3' || $linkp == 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}
..

Answer 5

'featuredimg-3' will always be evaluated as true, you have to try $linkp == 'whatever' in each or subcondition.
so :
if ( $linkp == 'featuredimg-1' || $linkp == 'featuredimg-3' || $linkp == 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
}

Answer 6

You'll need to specify the == operator for each condition in the or clause, otherwise, the string values such as 'featuredimg-3' will be evaluated on their own, and any non-empty string evaluates to true.
Also, when the choices are mutually exclusive, it is better to use elseif so that PHP can skip the remaining if statements when it matches one.
I've also added a final else, so you can see how you can do something in case none of the values match.
$linkp = opensky_featured_image_position();
if ( $linkp == 'featuredimg-1' ||
$linkp == 'featuredimg-3' ||
$linkp == 'featuredimg-4' ) {
echo '<h1>F - '. opensky_featured_image_position() .'</h1>';
} elseif ( $linkp == 'featuredimg-2' ) {
echo '<h1>L - '. opensky_featured_image_position() .'</h1>';
} elseif ( $linkp == 'featuredimg-5' ) {
echo '<h1>N - '. opensky_featured_image_position() .'</h1>';
} else {
echo '<h1>Invalid or missing image position</h1>';
}
You may also want to take a look at the switch/case structure.
Using arrays as others have suggested does allow for brevity and arguably readability. If you do use arrays, you may still need to check to ensure that you find a value in the array and handle the case if you don't.