PHP Multiple Ternary Operator Not Working as Expected

PHP multiple ternary operator not working as expected

Because what you've written is the same as:

echo (true ? 1 : true) ? 2 : 3;

and as you know 1 is evaluated to true.

What you expect is:

echo (true) ? 1 : (true ? 2 : 3);

So always use braces to avoid such confusions.

As was already written, ternary expressions are left associative in PHP. This means that at first will be executed the first one from the left, then the second and so on.

PHP Ternary Operators don't work as expected?

The ternary operator is left associative unlike most other languages such as C#. The code:

$active = is_null($param)
    ? true
    : is_string($param)
        ? (strtolower($param) === 'true')
        : true;

is evaluated as follows:

$active = ((is_null($param) ? true : is_string($param))
                                                        ? (strtolower($param) === 'true') : true);

You must explicitly add parenthesis to make sure ?: works the way it does in familiar languages:

$active = is_null($param)
    ? true
    : (is_string($param)
        ? (strtolower($param) === 'true')
        : true);

Stacking Multiple Ternary Operators in PHP

Others have already suggested the right way of doing it but if you really want to use ternary operator you need to use parenthesis as:

$province = 7;
 $Myprovince = (
 ($province == 6) ? "city-1" :
  (($province == 7) ? "city-2" :
   (($province == 8) ? "city-3" :
    (($province == 30) ? "city-4" : "out of borders")))
 );

Updated Link

Using nested ternary operators

Wrap it in parentheses:

$selectedTemplate = isset($_POST['selectedTemplate'])
                  ? $_POST['selectedTemplate']
                  : (
                       isset($_GET['selectedTemplate'])
                       ? $_GET['selectedTemplate']
                       : 0
                  );

Or even better, use a proper if/else statement (for maintainability):

$selectTemplate = 0;

if (isset($_POST['selectedTemplate'])) {
    $selectTemplate = $_POST['selectedTemplate'];
} elseif (isset($_GET['selectedTemplate'])) {
    $selectTemplate = $_GET['selectedTemplate'];
}

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However, as others have pointed out: it would simply be easier for you to use $_REQUEST:

$selectedTemplate = isset($_REQUEST['selectedTemplate'])
                  ? $_REQUEST['selectedTemplate']
                  : 0;

Conditional ternary operator malfunctions (PHP)

Documentation reads:

Note: It is recommended that you avoid "stacking" ternary expressions.
PHP's behaviour when using more than one ternary operator within a
single statement is non-obvious:

<?php
// on first glance, the following appears to output 'true'
echo (true?'true':false?'t':'f');

// however, the actual output of the above is 't'
// this is because ternary expressions are evaluated from left to right

// the following is a more obvious version of the same code as above
echo ((true ? 'true' : false) ? 't' : 'f');

// here, you can see that the first expression is evaluated to 'true', which
// in turn evaluates to (bool)true, thus returning the true branch of the
// second ternary expression.
?>

PHP ternary operator error

You need to add some parenthesis.

$b = 'a';
$c = 'd';
echo ($b == 'a') ? 2 : ($c == 'a' ? 1 : 0);

ternary multiple conditions with multiple values

About 1:

In PHP, || doesn't do what you might expect coming from JavaScript, because the result will always be a boolean. || implicitely converts its operands to booleans and returns the result.

To get the equivalent of a short-circuit || from JavaScript in PHP, you can use ?: (the so-called "Elvis operator" - x ?: y is a shorthand for x ? x : y):

$days = isset($dy['value']) || isset($days['value']) ? ($dy['value'] ?: $days['value']) : null;

I didn't change the first || because it's indeed a boolean operation, but I did replace the second.

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However I think there is a logic error in your code anyway, because if you have E_NOTICE error reporting on, PHP will complain anyway if $days['value'] is set and $dy['value'] isn't, because you are still accessing $dy['value'] even if isset($dy['value']) == false. So you would need to use, for example:

$days = (isset($dy['value']) ? $dy['value'] : null) ?: (isset($days['value']) ? $days['value'] : null);

(Assuming you also want to skip a value if it's falsy - according to how you are using the || it looks like it.)

If you don't care about notice errors at all (discouraged!) you could just use:

$days = $dy['value'] ?: $days['value'] ?: null;

PHP nested conditional operator bug?

It is recommended that you avoid
"stacking" ternary expressions. PHP's
behaviour when using more than one
ternary operator within a single
statement is non-obvious

From the PHP Manual under "Non-obvious Ternary Behaviour".

Ternary operators are evaluated left to right, so unless you add it the braces it doesn't behave as you expect. The following would work though,

return (true ? "a" : (false ? "b" : "c"));

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