How to replace "if" statement with a ternary operator ( ? : )?

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.

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';

if else php shorthand ?

Try this

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

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;