PHP object-oriented - built-in standard classes and ordinary data types converted to object types-PHP Tutorial-php.cn

PHP object-oriented - built-in standard classes and ordinary data types converted to object types

黄舟

Release： 2023-03-07 06:22:01

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Built-in standard classes

　PHPThere are many "ready-made classes", one of which is called the "built-in standard class". There is nothing "inside" this class.

class stdclass{  }

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<?php$obj1 = new stdclass();
var_dump($obj1);class A{}$obj2 = new A();
var_dump($obj2);?>

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Running result:

object(stdClass)[1]object(A)[2]

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You can see that it is no different from the ordinary class.

The built-in standard class is used to store some temporary simple data, such as:

$obj1->pp1 = 1;$obj2->port = &#39;3306&#39;;

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It can also be used to store data during type conversion.

Object type conversion

Other data types are converted to object types, and the result is: an object of the built-in standard class (stdclass) .
The syntax is:

$obj = (object)其他类型数据;

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Convert the array to an object: the key name of the array is used as the attribute name, and the value is the corresponding value of the object.

#Note: The attributes of digital subscripted data elements after being converted into objects cannot be obtained through object syntax, so conversion is not recommended.

<?php
$config = array(    &#39;host&#39; => "localhost",    &#39;port&#39; => 3306,    &#39;user&#39; => "root",    &#39;pass&#39; => "123",    &#39;charset&#39; => "utf8",    &#39;dbname&#39; => "yeoman",
);
$obj1 = (object)$config;
var_dump($obj1);
echo  "<br />单独取出user：" . $obj1->user;?>

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Running result:

object(stdClass)[1]  public &#39;host&#39; => string &#39;localhost&#39; (length=9)  public &#39;port&#39; => int 3306
  public &#39;user&#39; => string &#39;root&#39; (length=4)  public &#39;pass&#39; => string &#39;123&#39; (length=3)  
  public &#39;charset&#39; => string &#39;utf8&#39; (length=4)  public &#39;dbname&#39; => string &#39;yeoman&#39; (length=6)


单独取出user：root

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However, there are subscript elements in the array. If they are converted into objects, they cannot be obtained through object syntax.

<?php
$arr = array(&#39;pp1&#39; => 1, 5 => 12);
$obj2 = (object)$arr;
var_dump($obj2);
echo "<br />单独取出pp1：" . $obj2->pp1;//echo "<br />单独取出5：" . $obj2->5;//会报错！?>

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Running result:

$arr = array(&#39;pp1&#39; => 1, 5 => 12);
$obj2 = (object)
$arr;
var_dump($obj2);
echo "<br />单独取出pp1：" . $obj2->pp1;//echo "<br />单独取出5：" . $obj2->5;//会报错！?>

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nullConverted to object: empty object

$obj = (object)null;

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Convert other scalar data to objects: the attribute name is fixed "scalar", and the value is the value of the variable

<?php$v1 = 1;       
$v2 = 2.2;
$v3 = "abc";
$v4 = true;
$objv1 = (object)
$v1;    //整型转为对象类型
$objv2 = (object)
$v2;    //浮点型转为对象类型
$objv3 = (object)
$v3;    //字符串型为对象类型
$objv4 = (object)
$v4;    //布尔转为对象类型
var_dump($objv1); echo "<br />";
var_dump($objv2); echo "<br />";
var_dump($objv3); echo "<br />";
var_dump($objv4); echo "<br />";

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The running result is:

object(stdClass)[1]  public &#39;scalar&#39; => int 1
object(stdClass)[2]  public &#39;scalar&#39; => float 2.2
object(stdClass)[3]  public &#39;scalar&#39; => string &#39;abc&#39; (length=3)
object(stdClass)[4]  public &#39;scalar&#39; => boolean true

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