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How Does PHP Handle Array Pass-by-Value vs. Pass-by-Reference?
Understanding Array Pass-by-Value and Pass-by-Reference in PHP
In PHP, arrays play a crucial role in data manipulation. However, managing arrays can raise questions about their behavior when assigned to variables and passed as function arguments.
When Passing Arrays to Functions
When passing an array to a function or method, PHP creates a copy of the array. Any changes made to the array within the function will not affect the original array outside the function. To modify the original array, you need to pass it by reference using the ampersand (&) sign before the variable name.
Example:
function my_func(&$arr) {
$arr[] = 30;
}
$arr = array(10, 20);
my_func($arr);
var_dump($arr); // Output: [10, 20, 30]
When Assigning Arrays to Variables
Assigning an array to a new variable creates a new copy of the array. The new variable is not a reference to the original array.
Example:
$a = array(1, 2, 3); $b = $a;
In this case, $b is a copy of $a. Any changes made to $b will not affect $a.
Exception: Using Reference Assignment
PHP provides a syntax for assigning arrays by reference using the ampersand (&) sign. This creates a reference to the original array, allowing changes in either variable to affect both arrays.
Example:
$a = array(1, 2, 3); $b = &$a;
Now, $b is a reference to $a. Any changes made to either $a or $b will affect the other.
By understanding the pass-by-value and pass-by-reference mechanisms for arrays in PHP, you can effectively manage and manipulate data within your applications.
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