PHP is a server-side scripting language embedded in HTML. What distinguishes PHP from others like client-side Javascript is that its code is executed on the server side. What can PHP do?
At the lowest level, PHP can do anything that other CGI programs can do, such as collecting form data and generating dynamic pages. content, or sending and receiving cookies. Perhaps the most powerful and meaningful feature of PHP is its support for a wide range of databases. Writing a database-enabled Web page is incredibly simple.
The following databases are currently supported:
Adabas D InterBase Solid
dBase mSQL Sybase
Empress MySQL Velocis
FilePro Oracle Unix dbm
Informix PostgreSQL
PHP also supports "talking" with other services through protocols, like IMAP, SNMP, NNTP , POP3, and even HTTP. You can also open obscure network interfaces and interact with other protocols.
Mastering PHP is using your computer to make rules. Framework tp3.2/5.2
In structured programming, the program is designed around the task to be solved.
In object-oriented programming, the program is designed around the objects in the problem domain.
Object-oriented way of identifying things:
●Analogy---->Classification
Class is the abstraction of things Things are instances of classes (instantiation->new)
A class is a collection of objects with the same properties and behaviors
In software systems, we use classes to simulate entities in real life (there is a limit to simulation)
Classes do not exist in a real sense, but are conceptually defined by people for a long time
Strong language: mandatory (mandatory definition of data types)
Weak language: weakened (No mandatory definition required)
Custom class:
class Person [identifier] {
//Attribute
public $name;
public $birth;
/ /behavior
function useTools( ){
}
}
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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($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。

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)”。

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。


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