`Enum`

Often in PHP programs we have many related constants. For example, a color may be any value from the rainbow—these are ideally stored in an enum.

With some helpful properties, we can access information about the enum cases. The name property will return a string representation of the enum.

Example

This program specifies a Color enum with 3 possible cases: Orange, Magenta and Fuchsia. It is a little different than most Color enums.

Step 1 We assign the color variable "c" in our PHP program to the Orange case of the enum.

Step 2 We test the enum local variable with an if-statement. The test succeeds, as the enum is the Orange color.

Step 3 It is possible to use a match statement on an enum—this can lead to clearer, more compact code that is easier to maintain.

Step 4 The name property returns a string representation of the enum case. We can manipulate it like any other string.

enum Color {
    case Orange;
    case Magenta;
    case Fuchsia;
}

// Step 1: assign local variable to enum value.
$c = Color::Orange;

// Step 2: test enum value with if.
if ($c == Color::Orange) {
    var_dump($c);
}

// Step 3: use another enum value and then match it.
$c = Color::Magenta;
$result = match ($c) {
    Color::Orange => "o",
    Color::Magenta => "m",
    Color::Fuchsia => "f"
};
echo $result, "\n";

// Step 4: convert enum to string with name.
$name = $c->name;
$name_upper = strtoupper($name);
echo "{$name} {$name_upper}\n";enum(Color::Orange)
m
Magenta MAGENTA

Backed `enum`

It is sometimes useful to associate a value with each enum case. For example, a priority enum could have an integer indicating the importance of each case.

Here We specify that the Priority enum is backed by ints. We use the values 100, 50 and 0 for the backing ints.

Next We invoke the cases() function to get all the cases. We can then loop over the cases and print their names and values.

// Int-backed enum.
enum Priority: int {
    case Top = 100;
    case Medium = 50;
    case Bottom = 0;
}

// Get cases.
$cases = Priority::cases();
var_dump($cases);

// Loop over cases.
foreach (Priority::cases() as $c) {
    echo "Name = " . $c->name . ", Value = " . $c->value . "\n";
}

Programs written in PHP can use constants and even locals to designate possible values—enums are not required. But enums are helpful—they organize the possible cases in one place.

Enum

Example

Backed enum

`Enum`

Backed `enum`