A two-dimensional array, also known as a matrix, refers to one or more one-dimensional arrays defined within a one-dimensional array, that is, the elements in one array are another array; a two-dimensional array is essentially an array as An array of array elements is an "array of arrays", and the type specifier is "array name [constant expression] [constant expression]". There are two ways to declare a two-dimensional array: 1. Direct assignment, the syntax "$array name[row subscript][column subscript]=value;"; 2. Use array(), the syntax "$array name=array( Key name=>array(key name=>value));".
The operating environment of this tutorial: windows7 system, PHP8.1 version, DELL G3 computer
In php, the so-called second To put it simply, a one-dimensional array 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 principle of two-dimensional arrays 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]
".
The two-dimensional array and one-dimensional array are created in the same way, just replace the elements in the array with an array.
There are two ways to declare a two-dimensional array
"Directly assign values to array elements"
"array() function"
Let's introduce these two methods to you in detail through our actual code cases.
1. Directly assign values to array elements
We can pass the format of "$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]['姓名'] = '张三'; $array[0]['年龄'] = '25'; $array[0]['性别'] = '男'; $array[1]['姓名'] = '李四'; $array[1]['年龄'] = '21'; $array[1]['性别'] = '男'; $array[2]['姓名'] = '娜娜'; $array[2]['年龄'] = '22'; $array[2]['性别'] = '女'; var_dump($array); ?>
row subscripts
and of the two-dimensional array The column subscript
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: Both "row subscript" and "column subscript" are empty
<?php header("Content-type:text/html;charset=utf-8"); $array[][] = '张三'; $array[][] = '25'; $array[][] = '男'; $array[][] = '李四'; $array[][] = '21'; $array[][] = '男'; $array[][] = '娜娜'; $array[][] = '22'; $array[][] = '女'; var_dump($array); ?>
Example 2 : "Row subscript" or "column subscript" are both empty
<?php header("Content-type:text/html;charset=utf-8"); $array[0][] = '张三'; $array[0][] = '25'; $array[0][] = '男'; $array[]['姓名'] = '娜娜'; $array[]['年龄'] = '22'; $array[]['性别'] = '女'; var_dump($array); ?>
2. Use the array() function
Declaring a two-dimensional array using the array() function is similar to declaring a one-dimensional array. The
array() function accepts a certain number of key=>value
parameter pairs separated by commas. The syntax format of a one-dimensional array is as follows:
$数组变量名 = array(key1 => value1, key2 => value2, ..., keyN => valueN);
The two-dimensional array is to change one or more value parameters in the one-dimensional array into array(....).
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); ?>
2) Associative array
<?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); ?>
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