How to modify the value of an array using references in PHP

In PHP language, array is one of the very important data structures. Usually we need to modify the array to meet different business needs. Sometimes, we need to modify the value of an array by reference. This article will introduce how to use references to modify the value of an array in PHP through examples.

1. What is a reference?

Reference is a very important concept in PHP. It is somewhat similar to a pointer in the C language. It is often used to pass function parameters and operate variables. . Using references avoids unnecessary memory overhead and data duplication.

In PHP, references are created using the & symbol, and the syntax is as follows:

$var =& $reference;

Here, $var is the variable name, and $reference is a reference to other variables. Usually, the values ​​of two variables point to the same memory address, so modifying the value of one variable will also modify the value of the other variable at the same time.

2. The use of references in PHP

In PHP, references are usually used to pass parameters to functions, or as function return values. In the following example, we will demonstrate modifying the value of an array by reference.

<?php
// 创建一个包含三个元素的数组
$array = array(&#39;apple&#39;, &#39;banana&#39;, &#39;cherry&#39;);

// 引用数组元素
$item =& $array[1];

// 修改数组元素的值
$item = &#39;orange&#39;;

// 输出修改后的数组
print_r($array);
?>

Execute the above code, we can see the following output:

Array
(
    [0] => apple
    [1] => orange
    [2] => cherry
)

In the above example, we created an array containing three elements, and then passed the second element of the array by reference The value of the element is modified to 'orange'. Finally, we output the modified array. We can see that the second element of the array has been successfully modified.

Let’s look at a more complex example. We will modify the value of a multi-dimensional array by reference.

<?php
// 创建一个包含多个元素的二维数组
$array = array(
    array(&#39;name&#39; => 'apple', 'price' => 0.5),
    array('name' => 'banana', 'price' => 0.3),
    array('name' => 'cherry', 'price' => 0.8)
);

// 循环遍历数组元素
foreach ($array as &$item) {
    // 将每个元素的价格增加10%
    $item['price'] *= 1.1;
}

// 输出修改后的数组
print_r($array);
?>

Execute the above code, we can see the following output:

Array
(
    [0] => Array
        (
            [name] => apple
            [price] => 0.55
        )

    [1] => Array
        (
            [name] => banana
            [price] => 0.33
        )

    [2] => Array
        (
            [name] => cherry
            [price] => 0.88
        )

)

In the above example, we created a two-dimensional array containing multiple elements and passed each element by reference. The price of elements has been increased by 10%. We can see that the price of each element of the array has been successfully modified.

3. Summary

This article introduces the use of references to modify the value of an array in PHP. By using references, we can avoid unnecessary memory overhead and data copying and achieve efficient operations on arrays. In actual development, we should use references as much as possible to improve the performance and readability of the code. If you have any questions or suggestions about the content of this article, please do not hesitate to leave a message in the comment area below and we will be happy to answer your questions.

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