Enum backed values in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an enum backed value in PHP?

An enum backed value in PHP is a way to assign a specific scalar value (like int or string) to each enum case, allowing the enum to hold and return that value.

beginner

How do you declare a backed enum with string values in PHP?

Use the syntax: enum Status: string { case Active = 'active'; case Inactive = 'inactive'; } where : string declares the enum as backed by strings.

intermediate

What happens if you try to assign a non-scalar value to a backed enum case?

PHP will throw a fatal error because backed enum cases must have scalar values (int or string) only.

beginner

How can you get the backed value of an enum case in PHP?

You can access the backed value using the ->value property, for example: Status::Active->value returns 'active'.

intermediate

Can backed enums have methods in PHP?

Yes, backed enums can have methods just like regular enums, allowing you to add behavior related to the enum cases.

Which scalar types can be used for backed enum values in PHP?

A int and string

B float and bool

C array and object

D resource and null

Backed enums in PHP only support int and string scalar types for their values.

How do you declare an enum backed by integers in PHP?

A enum Status { case Active = 1; case Inactive = 0; }

B enum Status: string { case Active = '1'; case Inactive = '0'; }

C enum Status: int { case Active = 1; case Inactive = 0; }

D enum Status: float { case Active = 1.0; case Inactive = 0.0; }

You declare an int backed enum by specifying ': int' after the enum name and assigning integer values to cases.

What will Status::Active->value return if enum Status: string { case Active = 'active'; }?

A 'active'

B Status::Active

C null

D An error

The ->value property returns the backed value assigned to the enum case, which is 'active'.

Can you assign a float value to a backed enum case in PHP?

A Only if you use a backed enum of type float

B Yes, float is allowed

C Only if you cast it to string

D No, only int and string are allowed

PHP backed enums only support int and string scalar types, float is not allowed.

What will happen if you try to assign an array as a backed enum value?

A It will assign the first element

B Fatal error

C It will be ignored

D It will convert to string

Backed enum values must be scalar (int or string). Assigning an array causes a fatal error.

Explain what a backed enum is and how you use it in PHP.

Think about enums that hold specific values like numbers or words.

Describe the rules and limitations for values assigned to backed enum cases in PHP.

Consider what types PHP allows for enum case values.