What is PHP's Reference Assignment Operator =& and How Does It Work?

Exploring the Reference Assignment Operator in PHP: =&

PHP provides the =& assignment operator, also known as reference assignment. This operator allows you to assign a reference to a variable instead of creating a copy.

What Does =& Do?

When you use the =& operator, you create a reference to the original variable. This means that any changes made to either the original variable or the reference variable are reflected in the other. Unlike a simple assignment (=), reference assignment does not create a new copy of the data but points both variables to the same memory location.

Is =& Deprecated?

Despite concerns raised in the past, the =& operator is not deprecated and remains a valid and widely used feature in PHP. It is the standard way to mirror changes between multiple variables, arrays, or objects.

Creating a Reference

To create a reference using =&, simply assign a reference to another variable:

$a = 3;
$b = &$a;

Now, any modification made to $a or $b affects both variables since they reference the same data.

Benefits of Reference Assignment

• Efficient memory usage: By avoiding copies, =& reduces memory consumption, especially when working with large datasets or objects.
• Real-time updates: Changes made to the referenced data are immediately reflected in all variables referencing it, ensuring synchronization.

Considerations and Limitations

• Careless usage: Using references carelessly can lead to confusion and unintended results. Ensure you only assign references when explicitly intended.
• Destructuring: When destructuring arrays or objects, references are not automatically preserved.
• PHP 5 Deprecation: As mentioned in the answer, assigning the result of 'new' by reference in PHP 5 is deprecated.

Visit the PHP manual's section on Assign By Reference for more detailed information and examples.

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