Reading notes-"Explaining PHP in detail"

"Explanation of PHP" - Electronic Industry Press

Chapter 1 Lamp website construction

Some advantages of Web applications:

Based on the browser, with a unified platform and UI experience.

No installation required, just have a browser to experience it.

Always use the current latest version of the app, no need to upgrade.

Data is permanently stored in the cloud, so there is basically no need to worry about losing it.

Main features of Web2.0:

Users participate in website content creation.

Web2.0 pays more attention to interactivity.

Website design that complies with web standards.

There is no absolute boundary between Web2.0 and Web1.0.

The core of Web 2.0 is not the technology, but the guiding ideology.

HTTP protocol:

The default port is TCP80.

The request process is divided into 4 steps: 1. Establish the connection; 2. Send the request information; 3. Receive the response information; 4. Close the connection.

HTTP message type: 1. Request message; 2. Response message.

HTTP message content: 1. Request/response line; 2. Request/response header; 3. Request/response body.

Commonly used web servers:

Apache, NGINX, IIS, Tomcat, Weblogic

Common website service platforms:

ASP .NET, JavaEE, LAMP

What PHP can do:

Server-side scripting, command line scripting, writing desktop applications

Features of PHP:

Can run on all major operating systems.

Supports a wide range of databases.

Supports the use of protocol services such as LDAP, SNMP, IMAP, POP3, etc.

Chapter 6 Basic Syntax of PHP

Variable variables:

$hi = "hello";
$$hi = "world";
echo "$hi $hello"; // 输出hello world，$$hi = $hello

Variable reference assignment:

$foo = "BOB";
$bar = &$foo;
$bar = "My name is Tom";
echo $bar; // 输出My name is Tom
echo $foo; // 输出My name is Tom

Note: PHP references are not like address pointers in C language, $bar and $foo have different entities in memory , just associate their respective values, refer to the example below.

$foo = 25;
$bar = &$foo;
unset($bar);
echo $foo; // 输出25

variable naming:

is case-sensitive, starts with a letter or underscore (not a number), cannot contain spaces, Chinese is allowed, keywords can be used as variable names (it’s just easy to confuse)

Variable type:

PHP is a weakly type-checked language, and the data type of a variable or constant is determined by the context of the program.

The above is an introduction to the reading notes - "PHP in detail", which includes various aspects. I hope it will be helpful to friends who are interested in PHP tutorials.