How to replace "if" statement with a ternary expression?

PHP 7+

The code in the question only makes sense if $address['street2'] doesn't exist. Otherwise one can write just echo $address['street2']; right away, without any conditions. Quite obviously, it will output either some address or nothing.

Therefore, one doesn't need empty() here, but only isset(). So correct expression would be

if (isset($address['street2'])) echo $address['street2'];

And for this expression, starting from PHP 7, there is a shorthand, called Null coalescing operator, which can be used like this :

echo $address['street2'] ?? '';

Which will output nothing (an empty string) if $address['street2'] doesn't exist, or output this variable's contents, which will be either some address or nothing.

Only when something specific has to be output in case the variable is empty, a ternary can be used:

echo !empty($address['street2']) ? $address['street2'] : 'Empty';

Basic True / False Declaration

$is_admin = ($user['permissions'] == 'admin' ? true : false);

Conditional Welcome Message

echo 'Welcome '.($user['is_logged_in'] ? $user['first_name'] : 'Guest').'!';

Conditional Items Message

echo 'Your cart contains '.$num_items.' item'.($num_items != 1 ? 's' : '').'.';

ref: https://davidwalsh.name/php-ternary-examples

It's the Ternary operator a.k.a Elvis operator (google it :P) you are looking for.

echo $address['street2'] ?: 'Empty'; 

It returns the value of the variable or default if the variable is empty.

The ternary operator is just a shorthand for and if/else block. Your working code does not have an else condition, so is not suitable for this.

The following example will work:

echo empty($address['street2']) ? 'empty' : 'not empty';

Quick and short way:

echo $address['street2'] ? : "No";

Here are some interesting examples, with one or more varied conditions.

$color = "blue";

// Example #1 Show color without specifying variable 
echo $color ? : "Undefined";
echo "<br>";

// Example #2
echo $color ? $color : "Undefined";
echo "<br>";

// Example #3
echo ($color) ? $color : "Undefined";
echo "<br>";

// Example #4
echo ($color == "blue") ? $color : "Undefined";
echo "<br>";

// Example #5
echo ($color == "" ? $color : ($color == "blue" ? $color : "Undefined"));
echo "<br>";

// Example #6
echo ($color == "blue" ? $color : ($color == "" ? $color : ($color == "" ? $color : "Undefined")));
echo "<br>";

// Example #7
echo ($color != "") ? ($color != "" ? ($color == "blue" ? $color : "Undefined") : "Undefined") : "Undefined";
echo "<br>";

Update in PHP 7+

// Check if the value exists
echo $_GET['user'] ?? "Undefined"; 
// Before isset($_GET['user']) ? $_GET['user'] : 'undefined';

// Multiple conditions can be added
echo $_GET['user'] ?? $_POST['user'] ?? $color ?? 'Undefined';

Note that when using nested conditional operators, you may want to use parenthesis to avoid possible issues!

It looks like PHP doesn't work the same way as at least Javascript or C#.

$score = 15;
$age = 5;

// The following will return "Exceptional"
echo 'Your score is: ' . ($score > 10 ? ($age > 10 ? 'Average' : 'Exceptional') : ($age > 10 ? 'Horrible' : 'Average'));

// The following will return "Horrible"
echo 'Your score is: ' . ($score > 10 ? $age > 10 ? 'Average' : 'Exceptional' : $age > 10 ? 'Horrible' : 'Average');

The same code in Javascript and C# return "Exceptional" in both cases.

In the 2nd case, what PHP does is (or at least that's what I understand):

1. is $score > 10? yes
2. is $age > 10? no, so the current $age > 10 ? 'Average' : 'Exceptional' returns 'Exceptional'
3. then, instead of just stopping the whole statement and returning 'Exceptional', it continues evaluating the next statement
4. the next statement becomes 'Exceptional' ? 'Horrible' : 'Average' which returns 'Horrible', as 'Exceptional' is truthy

From the documentation: http://php.net/manual/en/language.operators.comparison.php

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.

Conditional Welcome Message

echo 'Welcome '.($user['is_logged_in'] ? $user['first_name'] : 'Guest').'!';

Nested PHP Shorthand

echo 'Your score is:  '.($score > 10 ? ($age > 10 ? 'Average' : 'Exceptional') : ($age > 10 ? 'Horrible' : 'Average') );

You can do this even shorter by replacing echo with <?= code ?>

<?=(empty($storeData['street2'])) ? 'Yes <br />' : 'No <br />'?>

This is useful especially when you want to determine, inside a navbar, whether the menu option should be displayed as already visited (clicked) or not:

<li<?=($basename=='index.php' ? ' class="active"' : '')?>><a href="index.php">Home</a></li>

if else php shorthand ?

Try this

  ($value == 1) ? "selected" : "";

I think you used the brackets the wrong way. Try this:

$test = (empty($address['street2']) ? 'Yes <br />' : 'No <br />');

I think it should work, you can also use:

echo (empty($address['street2']) ? 'Yes <br />' : 'No <br />');

There's also a shorthand ternary operator and it looks like this:

(expression1) ?: expression2 will return expression1 if it evaluates to true or expression2 otherwise.

Example:

$a = 'Apples';
echo ($a ?: 'Oranges') . ' are great!';

will return

Apples are great!

Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.

From the PHP Manual

I think you probably should not use ternary operator in php. Consider next example:

<?php

function f1($n) {
    var_dump("first funct");
    return $n == 1;
}

function f2($n) {
    var_dump("second funct");
    return $n == 2;
}


$foo = 1;
$a = (f1($foo)) ? "uno" : (f2($foo)) ? "dos" : "tres";
print($a);

How do you think, what $a variable will contain? (hint: dos) And it will remain the same even if $foo variable will be assigned to 2.

To make things better you should either refuse to using this operator or surround right part with braces in the following way:

$a = (f1($foo)) ? "uno" : ((f2($foo)) ? "dos" : "tres");

Ternary Operator is basically shorthand for if/else statement. We can use to reduce few lines of code and increases readability.

Your code looks cleaner to me. But we can add more cleaner way as follows-

$test = (empty($address['street2'])) ? 'Yes <br />' : 'No <br />';

Another way-

$test = ((empty($address['street2'])) ? 'Yes <br />' : 'No <br />');

Note- I have added bracket to whole expression to make it cleaner. I used to do this usually to increase readability. With PHP7 we can use Null Coalescing Operator / php 7 ?? operator for better approach. But your requirement it does not fit.

I dont think i found the answer in all the above solutions. Some are also wrong.

To tests if a variable (or an element of an array, or a property of an object) exists (and is not null) use: echo isset($address['street2']) ? $address['street2'] : 'Empty';

To tests if a variable (...) contains some non-empty data use:
echo !empty($address['street2']) ? $address['street2'] : 'Empty';

If first variable($a) is null, then assign value of second variable($b) to first variable($a)

 $a = 5;
 $b = 10;   

 $a != ''?$a: $a = $b;

 echo $a;