Year: 2020

If you ever have to do a case-insensitive array sort in PHP, you will eventually notice that the results don’t match the MySQL latin1_swedish_ci collation. They just aren’t the same. The difference comes from a set of six characters that fall between the upper-case and lower-case alpha characters of ISO-8859-1.

Specifically, [ \ ] ^ _ ` are the troublemakers. A simple example would involve sorting the phrases “Hello” and “[Hello]”. In MySQL, “Hello” comes first. In PHP, “Hello” comes last.

If this is driving you crazy, all you will need to do is trick PHP into using an upper-case sort instead of a lower-case sort.

$strings = ['hello', '[Hello]', 'Hello'];
usort( $strings, 'mysql_simulator' );
var_dump( $strings );

function mysql_simulator( $a, $b ) {
    return strcmp( strtoupper( $a ), strtoupper( $b ) );
}

I hope this will save you some of the research in solving that pesky little difference.

It seems I’ve discovered a new kind of PHP error that isn’t documented anywhere on the web yet. Here is a simple example and explanation to help correct your code.

class MyClass {}
$obj = new MyClass;
$test1 = MyClass::class;    // Right
$test2 = get_class( $obj ); // Right
$test3 = $obj::class;       // Wrong

That last line in my code sample produces the following error in PHP 7.4.

Fatal error: Cannot use ::class with dynamic class name in […][…] on line 5

This is the PHP way of saying that you have to switch to the get_class() function when retrieving the fully qualified class name of an object.

Note: An existing RFC proposes to change this behavior in PHP 8, so this particular error message might not exist in some future versions.