PHP 7

PHP 7 is the next major version of the PHP language. You really should check it out and upgrade.

Why PHP 7 and not PHP 6?

Choosing the version 7 (instead of 6) was chosen because a lot of existing books were mentioning PHP 6 long before the development of the next major version after PHP 5 started. Andi Gutmans said “We’re going to skip version 6 because years ago, we had plans for a 6 but those plans were very different from what we’re doing now,” so the name PHP 7 was chosen.

Major changes

Most important changes from PHP 5:

Performance improvements - PHP 7 is significantly faster than previous versions.
Uniform Variable Syntax
Exceptions in the engine
Scalar type declarations
Combined comparison (spaceship) operator
Easy user-land CSPRNG
Null coalescing operator
Removed deprecated functionality from PHP 5

Be sure to read more about the changes in the migration chapter of PHP manual.

Uniform variable syntax

Thanks to AST (Abstract Syntax Tree) implemented in PHP7 now you can write expressions in the more predictable ways.

Following examples are not possible in PHP5

Chained function calls

$obj->someMethod()()()()();

Call a function by name returned from arbitrary expression

$var = 'Hello World!';
echo (is_string($var) ? 'strlen' : 'count')($var);

Call a callable created from array literal

echo [new ArrayObject($_SERVER), 'count']();

With uniform variable syntax, you can now do more operations on expressions.

Exceptions in the engine

In previous versions you couldn’t catch fatal errors. Now you can do this:

<?php

function doSomething($obj)
{
    $obj->nope();
}

try {
    doSomething(null)
} catch (\Error $e) {
    echo "Error: {$e->getMessage()}\n";
}

// Error: Call to a member function method() on a non-object

Scalar type declarations

Now you can enforce parameter types as strings (string), integers (int), floating-point numbers (float), and booleans (bool). Type declarations (previously known as type hints) in PHP 5 were class names, interfaces, array and callable.

<?php

// Coercive mode
function sum (int ...$numbers)
{
    return array_sum($numbers);
}

var_dump(sum(2, '3', 4.1)); // outputs 9

Besides coercive mode there is also strict mode which can be enabled per file basis with:

<?php

declare(strict_types=1);

Read more about type declarations in the PHP manual.

Combined comparison (spaceship) operator

The spaceship operator is used for three-way comparison of two expressions. It returns:

1 (if the left-hand operand is greater than the right-hand operand)
0 (if both operands are equal)
-1 (if the right-hand operand is greater than the left-hand operand)

Example of spaceship operator where you need to sort multidimensional array

To do this, you can use usort() with comparison function:

<?php

$items = [
    ['title' => 'Mouse'],
    ['title' => 'Computer'],
    ['title' => 'LCD Screen'],
];

// sort items by title
usort($items, function ($a, $b) {
    return $a['title'] <=> $b['title'];
});

Easy user-land CSPRNG

PHP 7 has two new functions random_bytes() and random_int() for generating cryptographically secure integers and strings in a cross platform way.

Before PHP 7 you had to use the generator on the platform. For example, CryptGenRandom on Windows and /dev/urandom on Linux. If you’re building modules that must work on all platforms, this might be an issue. In PHP 7 you can simply use the built-in generator.

Null coalescing operator

It turned out that often you needed to use ternary operator with isset() function.

An example where you need to check if the GET data has been sent and set the $username based on that. In PHP 5 you could do something like this:

<?php
$user = isset($_GET['user']) ? $_GET['user'] : 'Guest';

Now you can simplify this a lot:

<?php
$user = $_GET['user'] ?? 'Guest';