A brief analysis of two-dimensional array creation methods for PHP array learning

PHP supports one-dimensional and multi-dimensional arrays. In the previous article "PHP Array Learning How to Create and Initialize a One-Dimensional Array (Detailed Code Explanation)" we gave you a detailed introduction to one-dimensional arrays through code examples There are several methods of creating and initializing arrays, so let’s take a look at two-dimensional arrays (multi-dimensional arrays) in PHP and see how to create two-dimensional arrays (multi-dimensional arrays). Let’s learn together!

In this article, we will first introduce the creation method of two-dimensional array through code examples, and then expand on the creation method of multi-dimensional array. Let’s take a look below.

The so-called two-dimensional array, simply put, is to define multiple one-dimensional arrays inside a one-dimensional array, that is, the value in one array can be another array (it may be a bit one-sided, but the two-dimensional array The principle is roughly like this). A two-dimensional array is essentially an array with an array as an array element, that is, an "array of arrays", and the type specifier is "array name[constant expression][constant expression]". (Attachment: PHP function array array function video explanation)

1. Creation of two-dimensional array

2 The creation method of dimensional array and one-dimensional array is the same, just replace the elements in the array with an array. There are also two methods: "directly assigning values ​​to array elements" and "array() function". Below we will introduce these two methods in detail with our actual code examples.

1. Directly assign values ​​to array elements

We can use the form "$array variable name[row subscript][column subscript]= value ;” format to create and initialize the two-dimensional array

<?php
header("Content-type:text/html;charset=utf-8");
$array[0][&#39;姓名&#39;] = &#39;张三&#39;;
$array[0][&#39;年龄&#39;] = &#39;25&#39;;
$array[0][&#39;性别&#39;] = &#39;男&#39;;
$array[1][&#39;姓名&#39;] = &#39;李四&#39;;
$array[1][&#39;年龄&#39;] = &#39;21&#39;;
$array[1][&#39;性别&#39;] = &#39;男&#39;;
$array[2][&#39;姓名&#39;] = &#39;娜娜&#39;;
$array[2][&#39;年龄&#39;] = &#39;22&#39;;
$array[2][&#39;性别&#39;] = &#39;女&#39;;
var_dump($array);
?>

Output result:

Row subscript of the two-dimensional array and column subscripts can be empty (that is, no specific index value is specified), then the default is a numeric index, and the index value increases sequentially starting from 0 by default.

Example 1: "Column subscript" is empty

<?php
header("Content-type:text/html;charset=utf-8");
$array[0][] = &#39;张三&#39;;
$array[0][] = &#39;25&#39;;
$array[0][] = &#39;男&#39;;
$array[1][] = &#39;李四&#39;;
$array[1][] = &#39;21&#39;;
$array[1][] = &#39;男&#39;;
$array[2][] = &#39;娜娜&#39;;
$array[2][] = &#39;22&#39;;
$array[2][] = &#39;女&#39;;
var_dump($array);
?>

Output result:

Example 2: "Row subscript" is Empty

<?php
header("Content-type:text/html;charset=utf-8");
$array[][&#39;姓名&#39;] = &#39;张三&#39;;
$array[][&#39;年龄&#39;] = &#39;25&#39;;
$array[][&#39;性别&#39;] = &#39;男&#39;;
$array[][&#39;姓名&#39;] = &#39;李四&#39;;
$array[][&#39;年龄&#39;] = &#39;21&#39;;
$array[][&#39;性别&#39;] = &#39;男&#39;;
$array[][&#39;姓名&#39;] = &#39;娜娜&#39;;
$array[][&#39;年龄&#39;] = &#39;22&#39;;
$array[][&#39;性别&#39;] = &#39;女&#39;;
var_dump($array);
?>

Output result:

Example 3: "Row subscript" and "Column subscript" are both empty

<?php
header("Content-type:text/html;charset=utf-8");
$array[][] = &#39;张三&#39;;
$array[][] = &#39;25&#39;;
$array[][] = &#39;男&#39;;
$array[][] = &#39;李四&#39;;
$array[][] = &#39;21&#39;;
$array[][] = &#39;男&#39;;
$array[][] = &#39;娜娜&#39;;
$array[][] = &#39;22&#39;;
$array[][] = &#39;女&#39;;
var_dump($array);
?>

Output result:

2. Use the array() function

Use the array() function to declare a two-dimensional array and declare a one-dimensional array Arrays are similar.

1) Index array

<?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    array("张三",25,"男"),
    array("李四",21,"男"),
    array("娜娜",22,"女")
);
var_dump($array);
?>

Output result:

2) Associative array

Example 1 :

<?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    "学生1"=>array("张三",25,"男"),
    "学生2"=>array("李四",21,"男"),
    "学生3"=>array("娜娜",22,"女")
);
var_dump($array);
?>

Output result:

Example 2:

<?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    "学生1"=>array("姓名"=>"张三","年龄"=>25,"性别"=>"男"),
    "学生2"=>array("姓名"=>"李四","年龄"=>21,"性别"=>"男"),
    "学生3"=>array("姓名"=>"娜娜","年龄"=>22,"性别"=>"女")
);
 var_dump($array);
?>

Output result:

Instructions: Get the elements in the two-dimensional array

Just need to indicate the subscript of each dimension

<?php
header("Content-type:text/html;charset=utf-8");
$array = array
(
    array("姓名"=>"张三","年龄"=>25,"性别"=>"男"),
    array("姓名"=>"李四","年龄"=>21,"性别"=>"男"),
    array("姓名"=>"娜娜","年龄"=>22,"性别"=>"女")
);
 echo $array[0][&#39;姓名&#39;].&#39;同学的年龄为&#39;.$array[0][&#39;年龄&#39;].&#39;岁&#39;;
?>

Output result:

张三同学的年龄为25岁

2. Creation of multi-dimensional array

A multi-dimensional array is an array containing one or more arrays.

In a multi-dimensional array, each element in the main array can also be an array, and each element in the sub-array can also be an array.

With reference to the two-dimensional array, we can easily understand the creation method of the multi-dimensional array

Example: Creation of the three-dimensional array

<?php
header("Content-type:text/html;charset=utf-8");
$array = array(
        &#39;安徽&#39; => array(
            &#39;合肥&#39;=>array(&#39;蜀山区&#39;,&#39;长丰县&#39;,&#39;肥东&#39;),
			&#39;宿州&#39;=>array(&#39;墉桥区&#39;,&#39;灵璧县&#39;,&#39;泗县&#39;)
        ),
        &#39;河南&#39; => array(
            &#39;洛阳&#39;=>array(&#39;西工区&#39;,&#39;老城区&#39;,&#39;孟津县&#39;),
            &#39;郑州市&#39;=>array(&#39;中原区&#39;,&#39;金水区&#39;)
        )
);
 var_dump($array);
?>

Output result:

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