Summary of basic knowledge of PHP (necessary for beginners to get started)

PHP is a widely used open source, server-side-based scripting language that is used to generate dynamic web pages and can be embedded in HTML. It is especially suitable for WEB development. Let me share with you the basic knowledge of PHP that novices in PHP must know. It is super practical. Friends who are interested can learn it together.

Many people think that they are programmers when they see PHP, and they think that there is a lot of money (although this is true) ), but you should also consider whether you are suitable for this industry. Do you know what PHP is? What kind of functions does PHP have, and what can they be used for?

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What is PHP?

•PHP (PHP: Hypertext Preprocessor, abbreviation of Hypertext Preprocessor) , is a widely used open source, server-side-based scripting language that is used to generate dynamic web pages and can be embedded in HTML, especially suitable for WEB development.

•When the client makes a request to the server's program, the web server responds to the corresponding page according to the request. When the page contains a PHP script, the server will hand it over to the PHP interpreter for interpretation and execution, and the generated The html code is then sent back to the client, and the client's browser interprets the html code and finally forms a page in web format.

Execution method

• PHP code is enclosed in special start and end characters , so that the script of the web page can enter and exit the "PHP mode". Other scripts written in C or Perl require a large number of commands to write a program to output HTML, while writing an HTML script in PHP only requires embedding some code to complete the operation (for example, in this case, some text is output ).

•Different from Java on the client side, PHP code runs on the server side. If you build code similar to the example above on the server, after running the script, the client will receive the results, but they will not know how the code behind it works. You can even set up the web server to let PHP handle all HTML files, so the user has no way of knowing what the server is doing.

PHP running environment installation

1. Install PHP environment Linux+Apache+MySQL+PHP under Linux, and install PHP environment WAMP under Windows

2. Integrated environment*: Wamp

Recommended integrated environment tools for PHP development:

1.phpStudy V8.0.9.3 (Win64 bit)

2.phpStudy V8.0.9.3 (Win32 bit)

##Features of PHP

•Is an open source, server-side scripting language.

•Independent of the operating system and can run on almost any system.

•Supports most servers, such as Apache, IIS.

•Supports a large number of databases, mainly Access\MySQL\SQL Server.

•Can create images.

•… …

•There are also some other special features that will be introduced in detail later in the advanced technology.

•We know that large websites such as Xunlei and Xinliang Weibo use PHP programs.

C/S and B/S structure

C/S (Client/Server) structure, which is the well-known client phase server structure. It is a software system architecture that can make full use of the advantages of the hardware environment at both ends and reasonably allocate tasks to the Client side and the Server side for implementation, reducing the communication overhead of the system. At present, most application software systems have a two-layer structure in the form of Client/Server

B/S (Browser/Server) structure, which is a browser-server structure. It is a change or improved structure to the C/S structure with the rise of Internet technology. Under this structure, the user work interface is implemented through the WWW browser. A very small part of the transaction logic is implemented on the front end (Browser), but the main transaction logic is implemented on the server side (Server). This greatly simplifies the client computer load, reduces the cost and workload of system maintenance and upgrades, and reduces the overall cost for users.

Integrated development environment

WAMP

Apache+Mysql/MariaDB+Perl under Windows / PHP/Python, a set of open source software commonly used to build dynamic websites or servers, are independent programs themselves, but because they are often used together, they have increasingly higher compatibility, and together they form a powerful Web application platform.

MAMP

MAMP PRO under Apple system is a professional-level version of the classic local server environment os x software. The initials of MAMP represent Macintosh, Apache, MySQL and PHP on Apple's OSX system. As the name suggests, you should know the powerful functions of MAMP! MAMP includes Apache server, PHP installation package and MySQL installation package.

PHP tag style

f9cfb7530078340123117120ff7e17e5

This is the tag recommended for PHP style. Server administrators cannot disable this style of markup.

Convenient mixing with HTML

<?php
if ($expression) {
?>
<strong>This is true.</strong>
<?php
} else {
?>
<strong>This is false.</strong>
<?php }?>

PHP will directly output the end tag and the next start Any non-PHP code in the markup. When a large amount of text needs to be output, exiting PHP parsing mode will be more efficient than using echo() or print() or similar functions to print all the text.

Semicolon

PHP uses semicolons to separate simple statements. Use braces to mark blocks of code for compound statements, such as conditional tests or loops. Do not use a semicolon after the braces. Unlike other languages, the semicolon before the right bracket (?>) is not required in PHP.

White space and newline character

Generally speaking, white space character does not matter in PHP. You can expand a statement to any line, or compact the statement to a single line. You can take advantage of this flexible format to make your code more readable (by permuting allocations, indentation, etc.). Some lazy programmers take advantage of this free format to create code that is simply unreadable, and this is not recommended.

Program comments

PHP supports C, C++ and Shell script style comments, as follows:

•// Single-line comments

•/* ...*/ Multi-line comments (note: cannot be nested)

•# Script comments

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