What is php type hinting?
View Discussion Show Improve Article Save Article View Discussion Improve Article Save Article Type hinting is a concept that provides hints to function for the expected data type of arguments. For example, If we want to add an integer while writing the add function, we had mentioned the data type (integer in this case) of the parameter. While calling the function we need to provide an argument of integer type only. If you provide data of any other type, it will throw an error with clear instructions that the value of an integer type is needed. Advantages of type hinting:
Disadvantages of type hinting:
Example 1: In the following example, $var1 of type “cls” class is passed to the display() function. It displays the text of the class “cls”. PHP
Output: Hi welcome to php world Example 2: The following example shows that $numbers is passed as a parameter to the add() function which is of type array. All the array items are added using the PHP foreach() loop. PHP
Output: 20 If an integer is passed, the following error is thrown. Summary: in this tutorial, you’ll learn how to use PHP type hints to declare the types for function parameters and return values. Introduction to PHP type hintsPHP is a dynamically typed language. When you define a function, you don’t need to declare types for parameters. For example:
The If you pass two floating-point numbers into the
More interestingly, you can pass an integer and a numeric string into the
In this case, the
Error:
To enforce the types for function parameters and return value, you can use type hints. Note that PHP also allows you to use type hints for class properties and methods which you’ll learn in the PHP object-oriented programming tutorial. PHP type hints for function parametersThe type hints ensure that PHP will check the type of a value at the call time and throw a To add a type hint to a parameter, you place a type in front of it like this:
In PHP 5, you can use The following defines the
However, if you pass two floats, you’ll get the result as an integer:
In this case, PHP implicitly coerces By default, PHP coerces a value of the compatible type into the expected scalar type declaration if possible. To enforce the value with a type that matches the type declaration, you need to declare strict typing. PHP type hints for function’s return valueTo specify a return value’s type for a function, you add the type after the function header like this:
The following example defines the
Starting from PHP 7.0, if a function doesn’t return a value, you use the '; die; } The union typeStarting from PHP 8.0, if a function returns a value of several types, you can declare it as a union type. For example:
In this example, the The mixed typeIf a function returns a value of many types, you can use the mixed type. The mixed type means one of several types. The mixed type. It’s equivalent to the following union type:
The mixed has been available since PHP 8.0.0. For example, the filter_var() built-in function use both union type (array|int) and mixed type as the type hints:
The nullable typeThe following defines a function that accepts a string and returns the uppercase of that string:
If you pass an argument with null, you’ll get an error:
Error:
To fix this, you can make the $str parameter nullable like this:
The nullable type was introduced in PHP 7.1. PHP allows you to mark the type declarations and returns values as nullable by prefixing the type name with a question mark ( In the above example, we add the
Note that the mixed type already includes the null type. Therefore, you don’t need to include nullable mixed like this:
Also, doing so will result in an error. Summary
Did you find this tutorial useful? What are type hints?Introduction to Python type hints
It means that you need to declare types of variables, parameters, and return values of a function upfront. The predefined types allow the compilers to check the code before compiling and running the program.
When was type hinting added PHP?In May of 2010 support for scalar type hinting was added to the PHP trunk.
Does PHP have type safety?By this definition, PHP will never be type safe (PHP's compiler hardly prohibits any type errors). But that definition also isn't particularly useful to the majority of developers.
What is type declaration also known as type hinting?Type declarations
As of PHP 7 Type hinting is being referred to as Type declaration. PHP allows the developer to be more specific about what functions are getting and returning. You can optionally specify the type of parameters that the function needs and the type of result the function will return.
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