What is a two-dimensional array in php?

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

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

Example 2 : "Row subscript" or "column subscript" are both empty

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

2) Associative array

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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