The new null coalescing operator in PHP7: How to simplify the logical judgment of the code?

A very practical operator has been added to PHP7: null coalescing operator. This operator can be used to simplify logical judgments in the code, making the code more concise and readable.

Traditional logical judgment is usually implemented using the ternary operator or if-else statement. For example, if we want to get the value of a variable, if the variable exists, the value of the variable will be used, otherwise the default value will be used. Before PHP7, we might write code like this:

$value = isset($variable) ? $variable : $default;

Such code looks cumbersome and not intuitive enough. Using the null merging operator can make the code more concise and clear:

$value = $variable ?? $default;

Use the null merging operator. If $variable exists and is not null, the value of $variable is used; otherwise, the value of $default is used. . This one line of code is enough, greatly reducing the complexity of the code.

In addition to simplifying logical judgments, the null coalescing operator can also be used to obtain values ​​in an array. For example, we want to get the value corresponding to a key in the array. If the key exists, use its value, otherwise use the default value. Before PHP7, we might write code like this:

$value = isset($array['key']) ? $array['key'] : $default;

And using the null coalescing operator, we can write like this:

$value = $array['key'] ?? $default;

Similarly, such code is more concise and clear.

null The merge operator can be used in multiple nestings to meet complex logical judgment and value requirements. For example, we want to get the attribute value of an object, but the attribute may not exist, and the object itself may not exist. Before PHP7, we might need to write code like this:

$value = (isset($object) && isset($object->attribute)) ? $object->attribute : $default;

Now, we can simplify it to this:

$value = $object->attribute ?? $default;

Of course, if the nested logic is more complex, we still need to use the traditional if-else statement to handle.

It should be noted that the null coalescing operator only determines whether the variable is null, not whether the variable exists or is empty. If you just want to determine whether a variable exists or is empty, you still need to use the isset() or empty() function.

To sum up, the new null coalescing operator in PHP7 can greatly simplify the logical judgment in the code, making the code more concise and easier to read. However, when using it, you need to pay attention to the usage scenarios and restrictions of the operator to avoid unnecessary errors.

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