If null use other variable in one line in PHP

Question

Is there in PHP something similar to JavaScript\'s:

alert(test || \'Hello\');

So, when test is undefined or null we\'ll see Hello, otherwis

Answer 1

Null is false in PHP, therefore you can use ternary:

alert($test ? $test : 'Hello');

Edit:

This also holds for an empty string, since ternary uses the '===' equality rather than '=='

And empty or null string is false whether using the '===' or '==' operator. I really should test my answers first.

Answer 2

As per the latest version use this for the shorthand

$var = $value ?? "secondvalue";

Answer 3

I'm very surprised this isn't suggested in the other answers:

echo isset($test) ? $test : 'hello';

From the docs isset($var) will return false if $var doesn't exist or is set to null.

The null coalesce operator from PHP 7 onwards, described by @Yamiko, is a syntax shortcut for the above.

In this case:

echo $test ?? 'hello'; 

Answer 4

you can do echo $test ?: 'hello';

This will echo $test if it is true and 'hello' otherwise.

Note it will throw a notice or strict error if $test is not set but...

This shouldn't be a problem since most servers are set to ignore these errors. Most frameworks have code that triggers these errors.

---

Edit: This is a classic Ternary Operator, but with the middle part left out. Available since PHP 5.3.

echo $test ? $test : 'hello'; // this is the same
echo $test ?: 'hello';        // as this one

This only checks for the truthiness of the first variable and not if it is undefined, in which case it triggers the E_NOTICE error. For the latter, check the PHP7 answer below (soon hopefully above).

Answer 5

From PHP 7 onwards you can use something called a coalesce operator which does exactly what you want without the E_NOTICE that ?: triggers.

To use it you use ?? which will check if the value on the left is set and not null.

$arr = array($one ?? 'one?', $two ?? 'two?'); 

Answer 6

If you want to create an array this way, array_map provides a more concise way to do this (depending on the number of elements in the array):

function defined_map($value, $default) {
    return (!isset($value) || is_null($value)) ? $default : $value;
    // or return $value ? $default : $value;
}

$values = array($one, $two);
$defaults = array('one', 'two');

$values = array_map('defined_map', $values, $defaults);

Just make sure you know which elements evaluate to false so you can apply the right test.