More than once, I've been amazed by what's actually built-into PHP. Here are some of my personal favourite functions.

Levenshtein

"Levenshtein" is the name of an algorithm to determine the difference — aka "distance" — between two strings. The name comes — unsurprisingly — from its inventor: Vladimir Levenshtein.

It's a pretty cool function to determine how similar two related words or phrases are. For example: passing in "PHP is awesome" twice, will result in a "distance" of 0:

levenshtein("PHP is awesome", "PHP is awesome"); // 0

However, passing in two different phrases will result in a larger distance:

levenshtein("Dark colour schemes", "are awesome"); // 13

Unsurprisingly, given how incompatible above two statements are 😉

Easter dates

PHP has — believe it or not — a built-in function to determine the date of Easter for any given year. Given that Easter's date is determined by "the first Sunday after the full Moon that occurs on or after the spring equinox", I'm in awe of PHP being able to calculate it for me.

Or maybe it simply is hard coded?

date('Y-m-d', easter_date(2023)); // 2023-04-08

Forks

Did you know PHP can be async? CLI versions of PHP have access to the pcntl functions, including the pcntl_fork function. This function is basically a wrapper for creating process forks, allowing one PHP process to spawn and manage several!

Here's a simple example using sockets to create an async child process in PHP:

function async(Process $process): Process {
    socket_create_pair(AF_UNIX, SOCK_STREAM, 0, $sockets);
    [$parentSocket, $childSocket] = $sockets;

    if (($pid = pcntl_fork()) == 0) {
        socket_close($childSocket);
        socket_write($parentSocket, serialize($process->execute()));
        socket_close($parentSocket);
        exit;
    }

    socket_close($parentSocket);

    return $process
        ->setStartTime(time())
        ->setPid($pid)
        ->setSocket($childSocket);
}

I actually wrote a little package that wraps everything in an easy-to-use API: spatie/async.

Metaphone?

Similar to levenshtein, methaphone can generate a phonetic representation of a given string:

metaphone("Light color schemes!"); // LFTKLRSXMS
metaphone("Light colour schemes!"); // LFTKLRSXMS

Built-in DNS

PHP understands DNS, apparently. It has a built-in function called dns_get_record, which does as its name implies: it gets a DNS record.

dns_get_record("stitcher.io");

{
    ["host"] => "stitcher.io"
    ["class"] => "IN"
    ["ttl"] => 539
    ["type"] => "NS"
    ["target"] => "ns1.ichtushosting.com"
}

// …

Recursive array merging

I mainly wanted to include array_merge_recursive because, for a long time, I misunderstood what it did. I used to think you'd have to use it for merging multidimensional arrays, but that's not true!

It might be better to let past-me explain it but, in summary, it works like this:

$first = [
    'key' => 'original'
];

$second = [
    'key' => 'override'
];

array_merge_recursive($first, $second);

{
    ["key"] => {
        "original",
        "override",
    }
}

Mail

PHP has a mail function. A function to send mail. I wouldn't use it, but it's there:

mail(
    string $to,
    string $subject,
    string $message,
    array|string $additional_headers = [],
    string $additional_params = ""
): bool

DL

Apparently, there's a function in PHP that allows you to dynamically load extensions, while your script is running!

if (! extension_loaded('sqlite')) {
    if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
        dl('php_sqlite.dll');
    } else {
        dl('sqlite.so');
    }
}

Blob… I mean glob

glob is a seriously awesome function: it finds pathnames according to a pattern. It's pretty easy to explain, but it's oh so useful:

glob(__DIR__ . '/content/blog/*.md');
glob(__DIR__ . '/content/*/*.md');

{
    /path/to/content/blog/foo.md,
    /path/to/content/other/bar.md,
    …
}

Sun info

Finally, PHP not only knows about Easter, it also knows about when the sun rises and sets, for any given date! It also requires a longitude and latitude, which of course makes sense because the sunrise and sunset times depend on your location:

date_sun_info(
    timestamp: strtotime('2023-01-27'), 
    latitude: 50.278809, 
    longitude: 4.286095,
)

{
  ["sunrise"] => 1674804140
  ["sunset"] => 1674836923
  ["transit"] => 1674820532
  ["civil_twilight_begin"] => 1674802111
  ["civil_twilight_end"] => 1674838952
  ["nautical_twilight_begin"] => 1674799738
  ["nautical_twilight_end"] => 1674841325
  ["astronomical_twilight_begin"] => 1674797441
  ["astronomical_twilight_end"] => 1674843622
}

What's your favourite PHP function? Let me know on Twitter!