Switch

Most languages have a switch statement or a similar construct. The PHP switch handles multiple cases: we have a variable, and test for many possible values.

With switch, we impart some symmetry to our programs. Usually we use "if" first, but in rewriting a program, changing to a switch may help it be more maintainable.

This program shows 3 versions of code that assigns a string to a literal value based on an integer. We test the bird_count integer.

Version 1 We use a switch statement on the bird_count, which is equal to 1. The second case (case 1) matches, and our string equals "One bird."

Version 2 We use match, a newer feature found in PHP 8. We handle the same cases but with "fat" arrow syntax.

Version 3 We use if-elseif to handle all the cases. This version can be changed to support "greater" and "less than" tests.

$bird_count = 1;

// Version 1: use switch to get bird count message.
$result = "";
switch ($bird_count) {
    case 0:
        $result = "No birds";
        break;
    case 1:
        $result = "One bird";
        break;
    case 2:
        $result = "Two birds";
        break;
    default:
        $result = "Many birds";
}
var_dump($result);

// Version 2: use match to get message string.
$result = match ($bird_count) {
    0 => "No birds",
    1 => "One bird",
    2 => "Two birds",
    default => "Many birds",
};
var_dump($result);

// Version 3: use if/elseif/else to get message string.
$result = "";
if ($bird_count == 0) {
    $result = "No birds";
} elseif ($bird_count == 1) {
    $result = "One bird";
} elseif ($bird_count == 2) {
    $result = "Two birds";
} else {
    $result = "Many birds";
}
var_dump($result);
string(8) "One bird"
string(8) "One bird"
string(8) "One bird"

In newer versions of PHP (like 8 onwards) we can use match instead of switch for clearer, simpler syntax. But switch still has some utility as it can support multiple statements in a case.