


Object-oriented programming in PHP: Methods for developing large-scale PHP projects (4) Author: Luis Argerich Translator: limodou Advanced OOP technology in PHP After looking at the basic OOP concepts, I can show you more advanced technologies: Serialization (Serializing) PHP does not support persistent objects. In OOP, a persistent object is an object that can maintain state and functionality among references in multiple applications. This means having the ability to save the object to a file or database and be able to use it later. Load the object. This is the so-called serialization mechanism. PHP has a serialization method that can be called on an object, and the serialization method can return a string representation of the object. However, serialization only saves the member data of the object and not the methods. In PHP4, if you serialize the object into the string $s, then release the object, and then deserialize the object into $obj, you can continue to use the object's methods! I don't recommend doing this because (a) there is no guarantee in the documentation that this behavior will still work in future versions. (b) This may lead to a misunderstanding when you save a serialized version to disk and exit the script. When you later run this script, you cannot expect that when you deserialize an object, the object's methods will be there, because the string representation does not include methods at all. In short, serialization in PHP is very useful for saving member variables of objects. (You can also serialize related arrays and arrays into a file). example: ------------------------------------------------ -------------------------------- ------------------ -------------------------------------------------- --------------- You restored the member data, but not the methods (according to the documentation). This results in the only way to access member variables (you have no other way!) by something like using $obj2->x, so don't try it at home. There are some ways to solve this problem, I left them out because they are too bad for the purpose of this concise article. I will happily welcome fully serialized features in subsequent versions of PHP. Reprinted from PHPBuilder.com

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。

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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