syntax - What is the meaning of three dots (...) in PHP?

Question

While I am installing Magento 2 on my Server, I got an error. After investigating the code and found that there is are three dots (...), which is producing the error. I included the code I found below:

return new $type(...array_values($args));

Answer 1

The ...$str is called a splat operator in PHP.

This feature allows you to capture a variable number of arguments to a function, combined with "normal" arguments passed in if you like. It's easiest to see with an example:

function concatenate($transform, ...$strings) {
    $string = '';
    foreach($strings as $piece) {
        $string .= $piece;
    }
    return($transform($string));
}

echo concatenate("strtoupper", "I'd ", "like ", 4 + 2, " apples");
// This would print:
// I'D LIKE 6 APPLES

The parameters list in the function declaration has the ... operator in it, and it basically means " ... and everything else should go into $strings". You can pass 2 or more arguments into this function and the second and subsequent ones will be added to the $strings array, ready to be used.