PHP Operators: Null Coalescing (??) and Spaceship (<=>)

PHP 7 introduced two powerful operators that significantly simplify common coding tasks: the null coalescing operator (??) and the spaceship operator (<=>). These operators provide cleaner, more concise alternatives to verbose conditional statements, improving code readability and efficiency.

The Null Coalescing Operator (??)

The null coalescing operator (??) is a shorthand for a common ternary operation that checks if a variable is set and not NULL. It returns the left operand if it exists and is not NULL; otherwise, it returns the right operand. This is particularly useful when dealing with potentially undefined array keys or variables.

How it Works

The syntax is straightforward:

$variable = $left_operand ?? $right_operand;

An example:

// Old way (PHP < 7)
$name = isset($_GET['name']) ? $_GET['name'] : 'Guest';

// New way (PHP 7+)
$name = $_GET['name'] ?? 'Guest';

As you can see, the new syntax is far more concise and readable. It eliminates the redundant check with isset(), making the code cleaner and less prone to errors.

The Spaceship Operator (<=>)

The spaceship operator (<=>), also known as the combined comparison operator, is used for comparing two expressions. It returns an integer based on the comparison:

• 0 if the left and right operands are equal.
• 1 if the left operand is greater than the right.
• -1 if the left operand is less than the right.

This operator is often used for sorting functions and custom comparison logic, as it provides a standardized way to compare values. Unlike the strcmp() function, the spaceship operator works with integers, floats, strings, and other data types.

How this PHP Operator Works

The syntax is simple:

$result = $left_operand <=> $right_operand;

An example:

// Old way (PHP < 7)
function compare_legacy($a, $b) {
    if ($a < $b) {
        return -1;
    } elseif ($a > $b) {
        return 1;
    } else {
        return 0;
    }
}

// New way (PHP 7+)
function compare($a, $b) {
    return $a <=> $b;
}

// Usage in a sort function
$array = [3, 1, 4, 1, 5, 9];
usort($array, 'compare');
// $array is now [1, 1, 3, 4, 5, 9]

The spaceship operator streamlines the comparison logic, turning a multi-line conditional statement into a single, elegant line of code. This makes your custom sorting and comparison functions much more efficient to write and read.

Conclusions on PHP Operators

Mastering the null coalescing and spaceship operators is a key step in writing modern, clean, and efficient PHP 7 code. These operators not only simplify your syntax but also help reduce common bugs associated with traditional comparison methods.

Try them at home!