12. PHP Switch and Match

What you will learn

• How switch works, and the need for break
• The modern match expression
• How they differ
• When to use each

The switch statement

switch compares one value against several cases. Each case needs a break, or execution falls through into the next case. default runs when nothing matches.

<?php
$day = 3;

switch ($day) {
    case 1:
        $name = "Monday";
        break;
    case 2:
        $name = "Tuesday";
        break;
    case 3:
        $name = "Wednesday";
        break;
    default:
        $name = "Another day";
}

echo "Day $day is $name";

Grouping cases

Leaving out break on purpose lets several cases share code.

<?php
$day = "Sat";

switch ($day) {
    case "Sat":
    case "Sun":
        echo "Weekend";
        break;
    default:
        echo "Weekday";
}

A catch with switch

switch compares with loose equality (==), so type conversion can cause surprises. It also needs many lines for simple jobs.

The match expression (PHP 8)

match is a shorter, safer alternative. It returns a value, uses strict comparison (===), needs no break, and throws an error if no arm matches and there is no default.

<?php
$day = 3;

$name = match ($day) {
    1 => "Monday",
    2 => "Tuesday",
    3 => "Wednesday",
    default => "Another day",
};

echo "Day $day is $name";

The comma-separated arms mean the same as the long switch, in a quarter of the lines. Remember the semicolon after the closing brace.

Several values in one arm

<?php
$day = "Sun";

echo match ($day) {
    "Sat", "Sun" => "Weekend",
    "Mon", "Tue", "Wed", "Thu", "Fri" => "Weekday",
    default => "Unknown",
};

match(true) for ranges

To test conditions rather than exact values, match against true.

<?php
$score = 72;

$grade = match (true) {
    $score >= 90 => "A",
    $score >= 70 => "B",
    $score >= 50 => "C",
    default => "Try again",
};

echo $grade;

What if nothing matches?

Without a default, an unmatched match throws an UnhandledMatchError. That is useful: it stops silent mistakes. Add a default when an unknown value is expected.

switch versus match

Common mistakes

• Forgetting break in a switch.
• Forgetting the semicolon after a match block.
• Expecting match to convert types. "1" does not match 1.
• Leaving out default when unexpected values are possible.
• Putting several statements in a match arm. Use switch or if for that.

<?php
$code = 404;

echo match ($code) {
    200 => "OK",
    404 => "Not found",
    500 => "Server error",
    default => "Unknown",
};

Summary

• switch compares loosely and needs break.
• match (PHP 8) is shorter, strict, and returns a value.
• Use match(true) for ranges, and include default when needed.