What is PHP:
PHP is a scripting language that runs on computers. Its founder is Rasmus Ledolf. The first two PHP versions were developed by this person. The original intention of developing the PHP language was relatively simple. It is for maintaining personal web pages, counting traffic, etc. In order to accelerate development and optimization, the author released it on June 8, 1995, which is also open source.
What are the application scenarios of PHP:
PHP is a language with a wide range of applications, especially in the development of network programs. Generally speaking, PHP is mostly executed on the server side. By executing PHP programs, web pages are generated for browsers to read. In addition, it can also be used to develop command line scripts and user-side GUI applications. PHP can be executed on many different servers, operating systems, and platforms, and can also be combined with many database systems. There is no cost to use PHP. Yes, it is completely free. The official organization PHP Group provides complete program source code, allowing users to modify, compile, and expand it for use.
What are the main data types of PHP:
PHP mainly has the following four scalar types:
- Integer (integer)
- Floating point type (float)
- Boolean (boolean)
- String
Two composite types:
- Array (array)
- object
Two special types
- NULL
- resource
What are the commonly used function libraries in PHP:
The power of a language depends on clear and powerful function libraries and class libraries. The built-in diverse functions are one of the main features of PHP. These open code functions provide a variety of different functions, such as files processing, FTP, string processing, etc. The usage of these functions is similar to the C language (such as printf), which is one of the reasons why PHP is so popular.
In addition to the built-in functions, PHP also provides many extended function libraries (extensions), such as various database connection functions, data compression functions, graphics processing, etc. wait. Some extension function libraries need to be obtained from PECL (PHP Extension Community Library).
What are the mainstream open source frameworks for PHP:
The official framework of PHP is the Zend framework. It was developed in 2005 and has entered a mature stage. Although there is still controversy in the industry about the direction of the PHP framework, the use of the framework has become very common in actual production.
Other commonly used PHP frameworks include: Yii, CodeIgniter, CakePHP, Symfony, QeePHP/FleaPHP, ThinkPHP, CakePHP, etc. Using these frameworks can make projects faster and simpler to deploy and more agile development efficiency, but On the other hand, learning to use these frameworks requires additional learning costs.
What are the mainstream versions of PHP:
PHP has developed from 1.0.0 to today's 5.*.*, 6.0 is also under development; and 5.2.10 is no longer maintained and optimized; the current main versions are 5.3.10 and 5.4.0.
Main version reference.
Reference source:
Wikipedia
PHP Manual

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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