PHP Type Hinting

In simple words, type hinting means providing hints to function only to accept the given data type. Type hinting is a technique that allows us to make a function accept the required data type. PHP allows the use of "type hints" when property or instance variables are declared in a class and variables are declared in the function definition. Many people consider PHP to be a poorly typed language.

The PHP parser makes every effort to cast the variables into a compatible type. Therefore, if one of the values supplied is a string representation of a number and the other is a numeric variable, PHP will transform the string variable to numeric in order to perform the addition operation.

Type Casting

In PHP, you can specify the type of arguments that a function accepts, known as type casting in function parameters. This ensures that the inputs passed to the function are of the expected data type, helping reduce bugs and increasing code clarity.

Output:

First number: 6, Second number: 7, Product: 42

Function Arguments Type Hinting in PHP

Type declarations, or type hints, are a method of declaring the type of value that can be passed to a method in PHP. This is a means of finding errors early on and making sure that the function is getting data in the shape that is expected.

For instance, we may declare the alert() method as follows to ensure that the argument supplied to it is always a string:

Output:

ALERT: Wrong password

Type Hinting Class Properties in PHP

In PHP, you can also apply type declarations to class properties to ensure they always hold values of a specific type. This makes your code more dependable and aids in identifying type-related errors.

Output:

ALERT: Wrong password

Return Type Hinting in PHP

In PHP, you can specify the expected return type of a function or method using a return type declaration. Guaranteeing that the method returns the appropriate data type enhances code readability and avoids unexpected behaviour.

Output:

ALERT: Wrong password

Type Hints in One Example

When working with classes in PHP, you can apply type hinting to:

• Properties using PHPDoc (@var)
• Function parameters to enforce input types
• Function return values to ensure consistent output types

Example: Logger Class with Getters and Setters Using Type Hints

Output:

Database connection failed.