What are the two composite data types in PHP?-PHP Problem-php.cn

What are the two composite data types in PHP?

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Release： 2023-02-23 17:56:01

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In php, there are two composite data types, one is array and the other is object.

##Array: a collection of data of the same type;

Object (object): An object is an instance of a class, usually created using the new keyword.

Array(Recommended learning: PHP programming from entry to proficiency)

Collect a series of data, Form an operable whole, which is an array. The data in the array can be scalar data, arrays, objects, resources, etc. We generally call a single piece of data in an array an element, and elements are divided into two parts: index (key name) and value. The index (key name) can be a number or a string, and the value can be of any data type.

Array declaration

Format:

$a=array(值1,值2,值3,...);
//或
$a=array(key1=>值1,key2=>值2,key3=>值3,...);
//或
$a=array();
$a[索引]=值1;
$a[索引]=值2;
$a[索引]=值3;
...

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Example:

<?php
$a=array("a","b","c","d");
$b=array("a"=>1,"b"=>2);
$b["c"]=3;
var_dump($a);
var_dump($b);
?>

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Note:

The length of the number is dynamic. As long as you add a value to the array, the length of the array will automatically increase;

The value in the number can be changed at any time. , as long as a value is assigned to the specified unit, the original value of the unit will be overwritten; the

var_dump() function will output the structure of the array, and cannot output the value of the array individually.

Object (object)

Object is an instance of a class and is real. Objects are generally created using the new keyword.

Creation of objects

new 类名();

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Instance

<?php
class Dog{ //类
public $name="";
public $color="";
function __construct($name,$color){//构造函数
$this->name=$name;
$this->color=$color;
}
}
$xiao=new Dog("小黄","黄色");//创建对象
var_dump($xiao); //打印对象
?>

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