isset PHP isset($_GET['something']) ? $_GET['something'] : ''

It's commonly referred to as 'shorthand' or the Ternary Operator.

$test = isset($_GET['something']) ? $_GET['something'] : '';

means

if(isset($_GET['something'])) {
    $test = $_GET['something'];
} else {
    $test = '';
}

To break it down:

$test = ... // assign variable
isset(...) // test
? ... // if test is true, do ... (equivalent to if)
: ... // otherwise... (equivalent to else)

Or...

// test --v
if(isset(...)) { // if test is true, do ... (equivalent to ?)
    $test = // assign variable
} else { // otherwise... (equivalent to :)

In PHP 7 you can write it even shorter:

$age = $_GET['age'] ?? 27;

This means that the $age variable will be set to the age parameter if it is provided in the URL, or it will default to 27.

See all new features of PHP 7.

That's called a ternary operator and it's mainly used in place of an if-else statement.

In the example you gave it can be used to retrieve a value from an array given isset returns true

isset($_GET['something']) ? $_GET['something'] : ''

is equivalent to

if (isset($_GET['something'])) {
  $_GET['something'];
} else {
  '';
}

Of course it's not much use unless you assign it to something, and possibly even assign a default value for a user submitted value.

$username = isset($_GET['username']) ? $_GET['username'] : 'anonymous'

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