🧩 PHP Array Operators — Explained with Examples

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🧲 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

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📘 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.

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📊 List of PHP Array Operators

Operator	Name	Description	Example
+	Union	Combines arrays. Left keys overwrite right keys if they exist	$a + $b
==	Equality	True if both arrays have same key/value pairs, order doesn’t matter	$a == $b
===	Identity	True if arrays have same key/value and order	$a === $b
!=	Inequality	True if arrays are not equal	$a != $b
<>	Inequality	Same as !=	$a <> $b
!==	Non-identical	True if arrays don’t have same key/value or order	$a !== $b

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🧪 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.

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⚖️ 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.

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🧬 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.

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❗ 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.

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⛔ 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.

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🧠 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.

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📌 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.

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❓ 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.

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