The match expression appeared in PHP 8 and solves the same task as switch: it picks a result based on a variable's value. The constructs are similar, but match is shorter and works as an expression. Let's compare them on one example. Here is how you select a text by an order status with switch:

<?php

switch ($status) {
    case 'processing':
        $statusText = 'Order is being processed';
        break;
    case 'paid':
        $statusText = 'Order is paid';
        break;
    case 'new':
        $statusText = 'New order';
        break;
    default:
        $statusText = 'Unknown status';
}

The same thing with match takes less space, and the result goes straight into the variable:

<?php

$statusText = match ($status) {
    'processing' => 'Order is being processed',
    'paid' => 'Order is paid',
    'new' => 'New order',
    default => 'Unknown status',
};

match (value) {
  │
  ├── 'a' → result 1
  ├── 'b' → result 2
  ├── 'c' → result 3
  └── default → default result
}

To the left of the => arrow is the value to compare, and to the right is any expression that becomes the result. The default arm fires when no value matches and plays the role of else. If several values lead to the same result, they are listed separated by commas:

<?php

$type = match ($size) {
    'xs', 's' => 'small',
    'm' => 'medium',
    'l', 'xl' => 'large',
};

The main difference from switch is that match is an expression. The whole construct evaluates to a value, so the result can be assigned to a variable or returned from a function right away. switch cannot do this; it needs a separate variable or a return inside a case. There are other differences too:

• match compares values strictly, like the === operator, with no automatic type conversion. switch compares loosely, with ==.
• match executes exactly one arm, so no break is needed. In switch, without break, control falls through to the next case.
• If nothing matches in match and there is no default, the program terminates with an UnhandledMatchError. In the same case, switch does nothing.

Since match returns a value, its result is often returned straight from the function with return:

<?php

function countItems(int $count): ?string
{
    return match ($count) {
        1 => 'one',
        2 => 'two',
        default => null,
    };
}

print_r(countItems(2)); // => two

Technically you can always do without match, just as without switch. But when you need to pick a result by specific values of a variable, match expresses that intent most clearly, and such code is easier to read than a chain of elseif.

Implement a function calculateDeliveryCost() that takes a delivery country and a parcel weight in kilograms. The function should return the delivery cost.

Each country has two rates: one for parcels weighing up to and including 1 kg, and another for heavier parcels:

• 'canada': 600 for parcels up to 1 kg, 900 for the rest
• 'usa': 800 for parcels up to 1 kg, 1200 for the rest
• 'germany': 700 for parcels up to 1 kg, 1000 for the rest

If the country is unknown, the function should return null.

Function call examples:

<?php

calculateDeliveryCost('canada', 0.5); // 600
calculateDeliveryCost('canada', 2);   // 900
calculateDeliveryCost('usa', 1);      // 800
calculateDeliveryCost('france', 1);   // null

Hint: any expression can appear to the right of the => arrow, including the ternary operator.