The so-called magic function of PHP, simply put, is a method that has a specific name in PHP - all starting with two underscores, and the PHP interpreter will automatically find and run the method when it reaches a certain time. The most common magic function is of course the constructor method: __construct.
Method calling in PHP works like this. First, the PHP interpreter looks for methods on the class. If the method exists, PHP calls it. If not, then the magic function __call on the class is called (if this method exists). If __call fails, the parent class method is called, and so on.
It seems a bit too perverted to say this with red lips and white teeth. Let’s give an example. Look at the following code:
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public function __construct(){ echo "this is construct!n";} }
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In this test class test, there is only one constructor that outputs some dispensable garbage characters, and nothing else;
At this time, we instantiate it and call a * method. What do you think it will do? We do this right away and watch:
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$send-> atomBomb(); |
The result is conceivable, he will definitely tell you that there is no such method - we indeed do not have such a * method! The error message is as follows:
Debug Error: test.php line 9 – Call to undefined method test::atomBomb()Then let’s modify this class and add a __call method to see what happens:
代码如下 | 复制代码 |
function name:atomBomb arg:Array |
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…… class test{ public function __construct(){ echo "this is construct!n"; } public function __call($name,$arg){ echo “function name:”,$name,”n arg:”.$arg; } } … Repeat the above calling method: $send = new test(); $send-> atomBomb(‘ab’,9); |
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function name:atomBomb arg:Array |
And we can easily see that __call has two parameters. The first parameter: the name of the method to be called, and the second parameter: the parameters entered when calling the method (this place is an array).
I don’t know if you understand this much. I think if you do, you will definitely ask what is the use of this thing? What can we use it for?
Then let me give you an idea of how to use it - apply what you have learned! Just imagine, if you treat all tables in a database as objects and perform CURD operations on them, how many classes do you need to write? Of course, if your array library only has two tables, you can tell me that there are only two classes! But what if there are 108 tables (for example, dede has 108 tables), and 108 classes are entered manually? Obviously unscientific, what is the most expensive thing in the 21st century? --time!
We can definitely write a class, and the rest will be created automatically. I found a piece of code in IBM and simplified it. You can take a look. This is something written by a senior engineer.
代码如下 | 复制代码 |
class DBObject{ private $id = 0; private $table; private $fields = array(); function __construct( $table, $fields ) { $this->table = $table; foreach( $fields as $key ) $this->fields[ $key ] = null; } function __call( $method, $args ) { if ( preg_match( "/set_(.*)/", $method, $found ) ) { if ( array_key_exists( $found[1], $this->fields ) ) { $this->fields[ $found[1] ] = $args[0]; return true; } } else if ( preg_match( "/get_(.*)/", $method, $found ) ) { if ( array_key_exists( $found[1], $this->fields ) ) { return $this->fields[ $found[1] ]; } } return false; } function insert() { global $db; $fields = $this->table."_id, "; $fields .= join( ", ", array_keys( $this->fields ) ); $inspoints = array( "0" ); foreach( array_keys( $this->fields ) as $field ) $inspoints []= "?"; $inspt = join( ", ", $inspoints ); $sql = "INSERT INTO ".$this->table." ( $fields ) VALUES ( $inspt )"; $values = array(); foreach( array_keys( $this->fields ) as $field ) $values []= $this->fields[ $field ]; $sth = $db->prepare( $sql ); $db->execute( $sth, $values ); $res = $db->query( "SELECT last_insert_id()" ); $res->fetchInto( $row ); $this->id = $row[0]; return $row[0]; } //下边删除了3个方法分别是更新update,删除一个,删除全部(战地注) } $book = new DBObject( 'book', array( 'author', 'title', 'publisher' ) ); $book->delete_all(); $book->set_title( "PHP Hacks" ); $book->set_author( "Jack Herrington" ); $book->set_publisher( "O'Reilly" ); $id = $book->insert(); echo ( "New book id = $idn" ); $book->set_title( "Podcasting Hacks" ); $book->update(); $book2 = new DBObject( 'book', array( 'author', 'title', 'publisher' ) ); $book2->load( $id ); echo( "Title = ".$book2->get_title()."n" ); $book2->delete( );…… |

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。

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。

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。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。

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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