Unlock PHP 7.4: 7 Powerful Features to Simplify Your Code

Typed Property Declarations

PHP 7.4 allows class properties to declare their types, enabling strict type enforcement. Example:

<?php
class User {
  public int $age;
  public string $name;
}
$user = new User();
$user->age = 10;
$user->name = "Zhang San";
// The following will cause a type error
$user->age = "zhang"; // int required
?>

Arrow Functions

Anonymous functions can now be written with a concise arrow syntax, automatically inheriting variables from the surrounding scope.

<?php
$factor = 10;
$nums = array_map(fn($n) => $n * $factor, [1, 2, 3]);
// Result: [10, 20, 30]
?>

Array Unpacking

Arrays can be unpacked inside another array using the spread operator ( ...), simplifying merges.

<?php
$parts = ['apple', 'pear'];
$fruits = [
  'banana',
  'orange',
  ...$parts,
  'watermelon'
];
// Result: ['banana','orange','apple','pear','watermelon']
?>

Null‑Coalescing Assignment Operator

The ??= operator assigns a default value only when the variable is undefined or null, replacing a longer if (!isset(...)) { ... } construct.

<?php
$array['key'] ??= computeDefault();
?>

Numeric Literal Separators

Underscores can be placed inside numeric literals to improve readability for floats, decimals, hexadecimals, and binaries.

<?php
6.674_083e-11;   // float
299_792_458;     // decimal
0xCAFE_F00D;    // hexadecimal
0b0101_1111;    // binary
?>

Array‑Based strip_tags

The strip_tags function now accepts an array of allowed tags, making the API clearer.

<?php
strip_tags($str, ['p', 'a', 'div']);
?>

money_format Deprecation

The money_format function is deprecated; developers should use NumberFormatter from the intl extension as a modern replacement.

Remember to verify your PHP version to avoid runtime errors caused by deprecated features.