What are the similarities and differences in how different versions of PHP handle function return value types?

Different PHP versions have different processing of function return value types: before PHP 7: the return value type is only a hint and is not mandatory to check. PHP 7 and above: Return value type declaration is enforced, otherwise an exception is thrown.

Different versions of PHP handle differences in function return value types

In PHP, the return value type of a function is determined through the type declaration specified. Different PHP versions have certain differences in how they handle return value types.

Before PHP 7

Before PHP 7, the return value type was only a hint and no mandatory check was performed. In other words, even if a function is declared to return a value of a specified type, it can still return a value of any type.

PHP 7 and above

Starting from PHP 7, return value type declaration becomes mandatory. This means that if a function is declared to return a value of a specific type, it must return a value of that type, otherwise a TypeError exception will be raised.

Type declaration syntax

In PHP, use the type colon syntax to declare the return value type. For example:

function get_name(): string
{
    return "John Doe";
}

Practical case

Consider the following code example:

function sum(int $a, int $b): int
{
    return $a + $b;
}

In this example, the sum() function The declaration returns a value of type int. If you try to return a non-int value of a different type, a TypeError exception will be raised.

Conclusion

PHP 7 and above handle function return value types differently from earlier versions. PHP 7 and above enforce return type declarations, while earlier versions only treat it as a hint. When writing and maintaining PHP code, understanding these differences is critical to ensuring that your code is correct and robust.

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