A class in php refers to a representative of a common transaction; an object refers to a specific representative of a certain type of transaction, also called an instance; a method refers to a function created in a class structure, also called a member method , member function.
Detailed introduction:
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Class: class is the outermost structure that defines the object-oriented subject, and is also used to wrap the subject data and functions (functions). Class is the representative of a class of common transactions and represents the commonality of transactions.
Object: object is a specific representative of a certain type of transaction and a specific unit of actual data and functional operations. It is also called an instance.
Instantiation: new, the process of obtaining a specific instance that conforms to the abstract concept from an abstract concept.
Class member: member, refers to all contents in the class structure, there are three types of class members;
Method: method, which is essentially a function created in the class structure, also known as Member methods, or member functions.
Attribute: property is essentially a variable created in the class structure, also called a member variable.
Class constant: constant, essentially a constant created in the class structure.
Example:
<?php //使用class关键字 定义类 class Myclass{ //定义类的属性,前面必须要加访问修饰符 public $name='杜威'; //定义类的函数(方法),前面可以省略访问修饰符,默认是public public function show(){ //在方法中向访问属性,可以使用$this。 echo $this->name; //也可以使用这种 // $mynme=new Myclass(); // echo $mynme->name; } } //使用new关键字实例化类Myclass,下面两种方法都是可以的, //由于实例化对象没有保存,所以输出的时候都会显示 object (Myclass)[1] // new Myclass; // new Myclass(); $sb=new Myclass(); $sb->show(); //输出杜威 ?>
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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($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。

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。

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。

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。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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