New features of PHP7 version: solving undefined exceptions

PHP7 version, as the latest PHP version, brings many new features and improvements, one of which is to solve the common undefined exception problem in previous versions. In older versions of PHP, accessing undefined variables or constants would cause the script to terminate and throw a Notice level error. In PHP7, this situation has been optimized and the new Null coalescing operator and Null coalescing assignment operator have been introduced, which can handle undefined variables or constants more flexibly.

The Null coalescing operator (??) is a new operator introduced in PHP7, which can be used to simplify the judgment of whether a variable or constant is defined. If the left operand is null or undefined, the right operand is returned. The following sample code demonstrates how to use the Null coalescing operator to avoid undefined exceptions:

$name = $_GET['name'] ?? 'Guest';
echo $name;

In the above code, $_GET['name'] is a variable that may be undefined. By using the Null coalescing operator, we can avoid errors caused by directly accessing an undefined variable and set its default value to 'Guest'.

In addition to the Null coalescing operator, PHP7 also introduces the Null coalescing assignment operator (??=). This operator can assign a variable to a default value, which will only be assigned if the variable is undefined or null. The following is an example of using the Null merge assignment operator:

$age = $_POST['age'] ??= 18;
echo $age;

In this code, $_POST['age'] is a possibly undefined variable. If $_POST['age'] is undefined, $age is assigned a value of 18. This ensures that the value of the $age variable will not be empty and avoids potential undefined exceptions.

By introducing the Null merge operator and the Null merge assignment operator, the PHP7 version effectively solves the common undefined exception problem in the old version, making the code more robust and readable. Developers can handle the definition of variables or constants more flexibly, reduce unnecessary error prompts, and improve the reliability and stability of the code. I hope this article will be helpful to the new features of the PHP7 version.

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