How to replace array key names in php

In PHP, arrays are a very important data structure that are often used to store and process different types of data. In actual development, we often need to operate arrays to achieve what we want. Among them, replacing array key names is a common operation. This article will introduce how to replace array key names in PHP, and give practical application scenarios for demonstration.

1. Define an array

Before we start to introduce the replacement of array key names, let’s take a look at how to define an array. Arrays in PHP can be defined in two ways, using the array() function or using the [] symbol. The following is a sample code that uses the array() function to define an array:

$arr = array(
    "name" => "张三",
    "age" => 25,
    "gender" => "男"
);

An associative array is defined here, which contains 3 elements. Each element has a key and a value, representing the person's name and age respectively. and gender. Of course, there are other types of arrays, so I won’t list them all here.

2. Replace the key name of the array

The following describes how to replace the key name of the array. PHP provides a very convenient function array_combine(), which can combine two arrays into an associative array, with one array as the key name of the new array and the other array as the value of the new array. Of course, make sure that the two arrays have the same number of elements.

The sample code is as follows:

$old_keys = array("name", "age", "gender");
$new_keys = array("student_name", "student_age", "student_gender");

$arr = array(
    "name" => "张三",
    "age" => 25,
    "gender" => "男"
);

$arr_with_new_keys = array_combine($new_keys, $arr);

In this example, we define two arrays: $old_keys and $new_keys. $old_keys represents the key names in the original array, and $new_keys represents the new key names to be replaced. Then, we define an associative array $arr, which is the array we need to replace the key names. Finally, we use the array_combine() function to use $new_keys as the key name of the new array and $arr as the value of the new array, thus obtaining a new array $arr_with_new_keys with the key name replaced.

3. Application Scenarios

So, what are the practical application scenarios of replacing array key names? The following is an example. We will demonstrate the application of replacing array key names through a practical case.

Suppose we have an associative array of student information, and each student has a unique student ID as the key. Now, we need to replace the student number as the key name with the name. At this time, we can use the method of replacing the array key name.

The sample code is as follows:

$data = array(
    "20170101" => array(
        "name" => "张三",
        "age" => 20,
        "gender" => "男"
    ),
    "20170102" => array(
        "name" => "李四",
        "age" => 22,
        "gender" => "女"
    ),
    "20170103" => array(
        "name" => "王五",
        "age" => 21,
        "gender" => "男"
    )
);

$student_names = array();
foreach ($data as $key => $value) {
    $new_key = $value['name'];
    $data[$new_key] = $value;
    unset($data[$key]);
}

print_r($data);

In this example, we define an associative array $data, which contains the information of 3 students, with each student's student number as the only key. name. We want to replace the student number with the name, so we use a foreach loop to iterate through each element in the $data array.

In the loop, we first get the student's name $value['name'] and assign it to $new_key. Then we use $new_key as the new key name, and assign the original key name and the corresponding value to a new element in the $data array, that is, $data[$new_key] = $value. Finally, we use the unset() function to delete the original element from the $data array, that is, unset($data[$key]).

Run the above code, you can get the following results:

Array
(
    [张三] => Array
        (
            [name] => 张三
            [age] => 20
            [gender] => 男
        )

    [李四] => Array
        (
            [name] => 李四
            [age] => 22
            [gender] => 女
        )

    [王五] => Array
        (
            [name] => 王五
            [age] => 21
            [gender] => 男
        )

)

You can see that the original student number has been replaced by the student's name, so that we can more easily process student information Manage and query.

4. Summary

This article introduces how to replace array key names in PHP, as well as a practical application scenario of replacing array key names. Replacing the array key names can make the array more readable and manageable, allowing us to operate the data in the array more conveniently. In actual development, we should choose the appropriate method to operate arrays according to specific needs.

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