PHP Array Operators — Explained with Examples

Introduction – Why PHP Array Operators Matter

Arrays in PHP are powerful data structures that allow you to store multiple values. But when working with multiple arrays — such as merging user input, comparing datasets, or performing set operations — PHP’s array operators become essential tools.

In this guide, you’ll learn:

• How array operators work
• The difference between union and comparison operators
• Explained code examples with outputs
• Common use cases and tips

What Are Array Operators in PHP?

Array operators perform operations between arrays such as union (+), equality (==), and identity (===). These help you compare, combine, or test arrays in logic-based operations.

List of PHP Array Operators

Code Examples with Explanations

1. Union Operator (+)

$a = ["a" => 1, "b" => 2];
$b = ["b" => 3, "c" => 4];
$result = $a + $b;
print_r($result);

Output:

Array
(
    [a] => 1
    [b] => 2
    [c] => 4
)

Explanation:

• Union combines both arrays.
• If a key exists in both arrays, the value from the left-hand array ($a) is preserved.

2. Equality (==)

$a = ["x" => 1, "y" => 2];
$b = ["y" => 2, "x" => 1];

var_dump($a == $b); // true

Explanation:
Arrays are equal if they contain same key/value pairs, regardless of order.

3. Identity (===)

$a = ["x" => 1, "y" => 2];
$b = ["y" => 2, "x" => 1];

var_dump($a === $b); // false

Explanation:
Although $a and $b have same content, the order of elements is different, so === returns false.

4. Inequality (!=, <>)

$a = ["a" => 1];
$b = ["a" => 2];

var_dump($a != $b); // true
var_dump($a <> $b); // true

Explanation:
!= and <> are equivalent. They return true because values differ for the same key.

5. Non-identity (!==)

$a = ["key" => 100];
$b = ["key" => "100"];

var_dump($a !== $b); // true

Explanation:
Even though values look the same, one is an integer and the other is a string — so the arrays are not identical.

Best Practices

• Use + when merging arrays with unique keys.
• Use == when comparing values regardless of order.
• Use === for strict checks — including order and types.
• Avoid using + if keys might conflict without intention.

Summary – Recap & Next Steps

PHP array operators offer powerful ways to merge, compare, and validate arrays. They help ensure consistency in logic when dealing with user inputs, configurations, or combined datasets.

Key Takeaways:

• Use + to union arrays — left-hand array values dominate.
• Use == for loose comparison; === for strict comparison (type & order).
• != / <> and !== help detect differences in structure and values.

Real-World Relevance:
Used in form comparison, settings merging, access control lists, session validation, and data deduplication.

Frequently Asked Questions (FAQs)

What is the difference between == and === for arrays?
== checks if values and keys are same, regardless of order.
=== also requires the same order and types.

Can I merge arrays with numeric keys using +?
Yes, but be careful: numeric keys won’t be overridden like associative ones.
For merging properly, use array_merge().

Are != and <> the same in PHP?
Yes. Both check for inequality.

When does the union operator (+) keep values from the first array?
Always. If keys overlap, values from the left array are preserved.