The new null coalescing operator in PHP7: How to simplify the null detection operation of the code?

The new null coalescing operator in PHP7: How to simplify the null detection operation of the code?

When developing PHP applications, you often encounter situations where you need to check for nulls, such as obtaining form data entered by the user, obtaining data from database query results, etc. The previous writing method often required the use of the ternary operator or the isset() function to make judgments. The code looked lengthy and not concise enough. In PHP7, a new null merge operator ?? is added, which can simplify the null detection operation of the code and improve the readability and maintainability of the code.

Specifically, the null coalescing operator?? is used to determine whether a variable is empty and returns a default value if it is empty. Its syntax is as follows:

$value = $variable ?? $default;

In the above code, $variable is the variable that needs to be nulled, and $default is the default value. If $variable is empty, then $value will be assigned the value $default, otherwise $value will be assigned the value The value of $variable. Simply put, the null coalescing operator simplifies the process of determining whether a variable is null and provides a default value.

Below we use specific code examples to demonstrate how to use the null merge operator to simplify the null detection operation:

$username = $_POST['username'] ?? 'Anonymous';
echo "Welcome, " . $username;

In the above code, we obtain it through the $_POST global variable The username entered by the user and then using the null coalescing operator to determine if it is null. If the username is empty, $username will be assigned the value 'Anonymous', otherwise it will be assigned the username entered by the user. Then we output the welcome message through the echo statement.

Besides in the case of getting user input data, the null merge operator is also very useful when dealing with getting data from the database. The following is an example of using the null merge operator to obtain database query results:

$user = getUserFromDatabase($userId) ?? getDefaultUser();

In the above code, the getUserFromDatabase($userId) function is used to obtain user information from the database. If the acquisition fails Then return null. We use the null coalescing operator to compare the returned result with the return value of the getDefaultUser() function. If the result returned by getUserFromDatabase($userId) is empty, assign $user to the return value of the getDefaultUser() function, otherwise $ user is assigned the value returned by getUserFromDatabase($userId).

Through the above examples, we can see the simplicity and convenience of the null coalescing operator. Using it can avoid lengthy null operations and improve the readability and maintainability of the code.

It should be noted that the null coalescing operator can only be used to determine whether a variable is null. If you need to determine whether the values ​​of multiple variables are empty, you still need to use the ternary operator or the isset() function to make the determination.

In summary, the new null merge operator in PHP7 simplifies the null judgment operation of the code and improves the readability and maintainability of the code. In situations such as retrieving user-entered data, querying results from a database, etc., using the null merge operator can make the code more concise without losing clarity. In actual development, we should make full use of this feature to improve the efficiency and quality of code.

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