CODEWITHSUNDEEP
php
funk-shun
funk-shun

Reputation: 4421

PHP: What does a & in front of a variable name mean?

What does a & in front of a variable name mean?

For example &$salary vs. $salary

Upvotes: 62

Views: 33140

Answers (4)

Tahazzot
Tahazzot

Reputation: 1262

In the world of PHP, references are like magical mirrors, reflecting changes across your code. Let's unravel their mysteries with some whimsical examples:

LEARN MORE FROM OFFICIAL DOCS

Why do we use it?

We use &$var instead of $var when we want to pass a reference to the variable rather than its value. This allows changes made to the referenced variable within a function to affect the original variable outside the function, saving memory and improving performance, especially with large data structures. It's particularly useful when we need to modify variables directly within functions or when we want multiple functions to operate on the same variable.

Caution:

The caution is to ensure that the referenced variable remains in scope and doesn't get unset or reassigned while its reference is still being used, to avoid unexpected behavior or errors. So Understand it before use it.

1. The Tale of Hero and Villain

$hero = 'Harry';              // Our brave hero's name
$darkLord = &$hero;           // The villain takes on the hero's guise
$darkLord = "Behold, I am $darkLord, the Dark Lord";  // Embracing darkness

echo $darkLord;   // "Behold, I am Harry, the Dark Lord"
echo $hero;       // Also echoes: "Behold, I am Harry, the Dark Lord"

Here, $darkLord and $hero share the same identity, revealing the duality of our characters.

2. Forbidden Spells: Restrictions on References

$age = 25;
$referenceToAge = &$age;      // Perfectly acceptable

$referenceToCalculation = &(24 * 7);  // Forbidden incantation; referencing an unnamed expression

function getAge() {
   return 25;
}

$referenceToFunction = &getAge();    // Spells backfire; can't directly reference a function return

3. The Enigma of Passing References

function changeName(&$person) {
  $person = 'Voldemort';
}

$name = 'Harry';

changeName($name); // Alas! The hero falls to the dark side

echo $name; // "Voldemort" rises, echoing across the realm

But beware! Passing anything other than a variable reference unleashes chaos.

4. Quest for Precision: Named Variables Only

$powerLevel = 9000;                      // Our hero's power level
$referenceToPowerLevel = &$powerLevel;   // Power harnessing at its finest

$referenceToExpression = &(10 * 5);      // Quest halted; can't reference an unnamed expression

function getPowerLevel() {
   return 9000;
}

$referenceToFunction = &getPowerLevel(); // Journey thwarted; can't directly reference a function return

5. The Saga of Shared Secrets: Arrays and References

$teamA = ['Gandalf', 'Frodo', 'Aragorn'];    // Fellowship of the Ring
$teamB = &$teamA;                             // Allies bound by fate

array_push($teamB, 'Legolas');                // A new member joins the fellowship

print_r($teamA);   // The roster echoes across Middle-earth
print_r($teamB);   // Both teams share the same quest

In the realm of arrays, references forge unbreakable bonds, uniting allies in their quest.

6. The Legend Lives On: Persistent References

function &createEternalFlame() {
    static $flame;                      // Eternal flame, ever-burning
    
    if (!$flame) {
        $flame = 'Eternal Flame';       // Igniting the essence of eternity
    }
    
    return $flame;                      // A beacon of hope for all who seek it
}

$torch = &createEternalFlame();         // Harnessing the essence of eternity

echo $torch;    // "Eternal Flame" illuminates the darkness

With static references, legends are born, immortalizing their essence throughout time.

------------ LEARN MORE ------------

Upvotes: 2

Sam Day
Sam Day

Reputation: 1719

It is used to pass a variable by reference.

Read more in the PHP documentation.

Upvotes: -2

Randy the Dev
Randy the Dev

Reputation: 26740

It passes a reference to the variable so when any variable assigned the reference is edited, the original variable is changed. They are really useful when making functions which update an existing variable. Instead of hard coding which variable is updated, you can simply pass a reference to the function instead.

Example

<?php
    $number = 3;
    $pointer = &$number;  // Sets $pointer to a reference to $number
    echo $number."<br/>"; // Outputs  '3' and a line break
    $pointer = 24;        // Sets $number to 24
    echo $number;         // Outputs '24'
?>

Upvotes: 88

rmeador
rmeador

Reputation: 25724

It's a reference, much like in other languages such as C++. There's a section in the documentation about it.

Upvotes: 3

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