The content of this article is about PHP singleton and factory mode, which has certain reference value. Now I share it with everyone. Friends in need can refer to it
Factory mode:
<?php interface persion{ public function say(); } class man implements persion{ public function say(){ echo 'i am man'; } } class factory{ public static function createman(){ return new man(); } } $obj = factory::createman(); $obj->say();
Factory mode, what is often used is to change the name of the man class. You only need to change the content of the createman class in the factory class. There is no need to change other places where the class is called. The factory mode actually just calls the class again. Another layer of factory class is added between the place and the class. The calling address directly calls the factory class
Single case mode:
Single column mode is often used to connect to the database class, such as:
<?php class Database { // 声明$instance为私有静态类型,用于保存当前类实例化后的对象 private static $instance = null; // 数据库连接句柄 private $db = null; // 构造方法声明为私有方法,禁止外部程序使用new实例化,只能在内部new private function __construct($config = array()) { $dsn = sprintf('mysql:host=%s;dbname=%s', $config['db_host'], $config['db_name']); $this->db = new PDO($dsn, $config['db_user'], $config['db_pass']); } // 这是获取当前类对象的唯一方式 public static function getInstance($config = array()) { // 检查对象是否已经存在,不存在则实例化后保存到$instance属性 if(self::$instance == null) { self::$instance = new self($config); } return self::$instance; } // 获取数据库句柄方法 public function db() { return $this->db; } // 声明成私有方法,禁止克隆对象 private function __clone(){} // 声明成私有方法,禁止重建对象 private function __wakeup(){} } $config = array( 'db_name' => 'test1', 'db_host' => 'localhost', 'db_user' => 'root', 'db_pass' => '' ); //获取数据库连接句柄 $obj = database::getInstance($config); $db = $obj->db();
A simple understanding of the singleton mode is to make the constructor of the class a private property, so that direct external instantiation can be prohibited, and then create a static method in which to determine whether the current class has an instantiated object. If not, instantiate yourself, then assign it to a class attribute and return it. If it is instantiated, return the instantiated object directly
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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($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。

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。

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)”。


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