How to declare the type of a custom PHP function?

PHP 7 introduces type declarations, allowing you to declare the types of function parameters and return values. Syntax: functionName(type $parameter1, type $parameter2, ...): type, supported data types: int, float, bool, string, array, object, null. Benefits: Improved readability, maintainability, and support for IDE integration.

#How to declare the type of a custom PHP function?

PHP 7 introduced type declarations, allowing you to specify types for a function’s parameters and return value. This helps make your code more readable and maintainable, and can prevent errors.

Syntax of type declaration

The declaration of a function type is located between the function name and brackets, in the following format:

function functionName(type $parameter1, type $parameter2, ...): type

• functionName is the function name.
• type is the type of parameter or return value.

Supported types

PHP supports the following data types:

• int(integer)
• float (Floating point number)
• bool (Boolean value)
• string (String)
• array(array)
• object(object)
• null(null value)

Practical case

Consider the following function, used to calculate the sum of two numbers:

function add(int $num1, int $num2)
{
    return $num1 + $num2;
}

We declare $num1# The ## and $num2 parameters are of type int, and the return value is declared to be of type int as well. This means that we expect the number passed to the function to be an integer, and the function will return an integer.

Type checking

PHP will automatically perform type checking. If the type of a function's parameters or return value does not match the declared type, a

TypeError exception will be thrown.

For example, if we try to pass a string argument to the

add function, the following exception will be thrown:

TypeError: Argument 1 passed to add() must be of the type integer, string given

Benefits

Declaring the type of a function has the following benefits:

• Readability: It makes the code easier to understand because you don't have to guess the types of the function's parameters and return values.
• Maintainability: It helps prevent errors because the compiler or interpreter will check the type and throw an error.
• IDE Integration: Modern IDEs, such as PhpStorm, support type declarations and can provide code completion and error checking based on type signatures.

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