This article organizes and summarizes the commonly used magic methods in PHP in detail and shares them with you for your reference. The specific content is as follows
1. PHP treats all methods starting with "__" as magic methods, so any custom methods cannot start with "__"
Overloading provided by PHP refers to dynamically creating attributes or methods. Overloading is achieved through magic methods. The parameters of these magic methods cannot be passed. __get(), __set(), __isset(), __unset() implements class attribute overloading.
2. When accessing an inaccessible attribute in a class, the __get() method will be called
3. When accessing inaccessible attributes in a class, __get(), __set(), __isset(), __unset() will be called according to different situations. When accessing attributes, use the function isset() or empty() When using the unset() function, the __isset() method will be called.
4. These four methods cannot be defined using the static keyword. After php5.3.0, a warning level warning will occur when the static method is used to define these four methods.
5. What are inaccessible attributes: (1) attributes that are not in the class, (2) private variables are accessed outside the class. Method overloading is implemented through __call() and __callstatic(). The difference between the two is whether a context is a static method. The latter will be called when an inaccessible static method is called. __callstatic() was added in php5.3.0.
6. __sleep() and __wakeup()
When serialize() is serializing, it will first check whether the __sleep() function exists. If it exists, it will first call __sleep() and return an array containing all variable names. If the method does not return anything, null will be serialized. ization and generate a notice-level error.
The __wakeup() method is the opposite of __sleep() and is called when unserialize() is called
7. __toString(), let a class decide how to convert it into a string. Before php5.2.0, this method can only be effective in combination with the echo or print method. After php5.2.0, it can be combined with printf() modification, but when modifying Non-character modifiers such as %d cannot be used.
8. __invoke(), when trying to call an object by calling a function, this function will be triggered. It only takes effect after php5.3.
9. __set_state() static method. This static method will only be called when var_export() is called. It will take effect after php5.1.0. The only parameter is to receive an array.
10. __construct() and __destruct(), constructor and destructor. The constructor is mainly used for class initialization. The destructor runs after all references to an object are deleted or when the object is explicitly destroyed. Exceptions are not allowed to be thrown in the destructor, otherwise a fatal error will be triggered. The destructor is called at the end of the script, when all http headers have been sent.
11. __clone(), object copy, this method cannot be called directly, it must be called explicitly through the clone keyword
Code:
//实例化对象时,会调用对象的__construct方法 $obj = new Object(); //给对象不存在的属性赋值时,会调用对象的__set方法 $obj->title = "hello"; //使用对象不存在的属性时,会调用对象的__get方法 echo $obj->title; //调用对象不存在的方法时,会调用对象的__call方法 $obj->test("hello",123,567); //调用不存在的类静态方法时,会调用类的__callStatic方法 Object::staticMethod("static","not found method"); //直接输出对象时,会调用对象的__toString方法 echo $obj; //将一个对象当作函数一样使用时,会调用对象的__invoke方法 echo $obj("test"); //克隆对象时,会调用对象的__clone方法 $obj2 = clone $obj; //判断对象属性是否存在时,会调用对象的__isset方法 var_dump(isset($obj->aaa)); //销毁对象属性时,会调用对象的__unset方法 unset($obj->aaa); class Object{ protected $array = array(); function __construct() { echo __METHOD__."你正在实例化对象<br>"; } function __set($name, $value) { $this->array[$name]=$value; } function __get($name) { return $this->array[$name]; } function __call($name, $arguments) { var_dump($name,$arguments); return "magic function\n"; } static function __callStatic($name, $arguments) { var_dump($name,$arguments); return "magic static function"; } function __toString() { return __CLASS__.'<br>'; } function __invoke($arguments) { var_dump($arguments); return __METHOD__.'<br>'; } function __clone() { echo __METHOD__."你正在克隆对象<br>"; } function __isset($name) { echo __METHOD__."你想判断有没有属性".$name."<br>"; return 1; } function __unset($name) { echo __METHOD__."你想删除属性".$name."<br>"; } function __destruct() { echo __METHOD__."你正在注销对象<br>"; } }
The above is all about the common magic methods in php. I hope it will be helpful to everyone's learning.

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


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