Can a function modify the original value of a passed variable in PHP?

User 2:
Hey there,

I completely understand your confusion about this concept in PHP. So, to answer your question, yes, a function can modify the original value of a passed variable in PHP if it is passed by reference.

Let me elaborate with a personal experience I had. I was working on a project where I needed to update the value of a variable from within a function. Initially, I was unaware of pass-by-value and pass-by-reference in PHP, so I encountered some unexpected behaviors.

Later, I discovered that by explicitly passing the variable by reference using the ampersand symbol, I was able to modify its value within the function. It was as simple as prefixing the parameter's name in the function definition with an ampersand.

Here's a simplified example:

php
function changeValue(&$var) {

    $var = "New Value";

}



$originalVar = "Original Value";

echo "Before function call: " . $originalVar . "<br>";



changeValue($originalVar);

echo "After function call: " . $originalVar;

Before function call: Original Value

After function call: New Value

User 1:
Hello fellow PHP learner,

Yes, it is indeed possible for a function to modify the original value of a passed variable in PHP if it is passed by reference using the ampersand symbol. When you pass a variable by reference, any changes made to it within the function will affect the original variable outside of the function as well.

To demonstrate this, let's consider a simple example:

php
function modifyValue(&$variable) {

   $variable = "Modified value";

}



$originalValue = "Original value";

echo "Before function call: " . $originalValue . "<br>";



modifyValue($originalValue);

echo "After function call: " . $originalValue;

Before function call: Original value

After function call: Modified value

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User 3:
Hello PHP enthusiasts,

I'm glad to see this question being discussed here. In my experience with PHP, I have encountered situations where functions can indeed modify the original value of a passed variable. However, it is important to note that this behavior relies on passing the variable by reference using the ampersand symbol.

Allow me to share an instance where this concept proved useful to me. I was developing a web application that required sorting an array in descending order. I wanted to keep the original array intact, while also having a sorted version available for further processing.

To achieve this, I used the `rsort()` function that functions by reference. The `rsort()` function sorts an array in reverse order, directly modifying the original array. Here's an example:

php
$originalArray = [7, 2, 10, 5];

echo "Before sorting: ";

print_r($originalArray);



rsort($originalArray);

echo "After sorting: ";

print_r($originalArray);

Before sorting: Array ( [0] => 7 [1] => 2 [2] => 10 [3] => 5 )

After sorting: Array ( [0] => 10 [1] => 7 [2] => 5 [3] => 2 )

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