Several aspects of content can be included in the .php file

Contents that can be included in the php file: 1. The starting tag "", all PHP code must be written inside this pair of tags; 2. The semicolon ";" is the PHP statement The delimiter also represents the instruction for code execution; 3. Comments, including single-line comments "//", multi-line comments "/* */", and Shell comments "#"; 4. Line breaks, which can be enhanced Code readability; 5. Code segments (such as functions, etc.).

The operating environment of this tutorial: windows7 system, PHP8 version, DELL G3 computer

PHP is a super text preprocessing language ( Abbreviation for Hypertext Preprocessor).

What is a php file?

The name format of a php file is a programming language format, more technically speaking, a scripting language embedded in HTML text , the language style is similar to C language, and the syntax combines C, Perl, Java and PHP's own innovative syntax forms, and is often widely used by website programmers. This kind of file is generally executed on the server side, which can fully utilize the performance of the server and execute dynamic web pages faster than CGL and Perl. Its execution engine can also keep frequently accessed programs in the memory so that the user can access them next time. There is no need to recompile the program, just execute the retained code directly, which is very efficient.

The most powerful feature of the php file is its database integration layer. With this feature, it becomes very simple to use php files to create a web page with a database. The function of the php file also depends on its Compatibility with various databases, in addition to using HTTP communication, php files can also use IMAP, SNMP, POP3 and NNTP protocols.

How many contents does the php file contain?

1. Start and end tags. All PHP code must be written inside this pair of tags.

// 起始标签
<?php

// 结束标签
?>

2. ";": The semicolon is the delimiter of PHP statements. Also represents the instructions for code execution

$name = 'PHP中文网';
echo $name;

3. Comments:

PHP supports 3 comment styles: C, C and Unix Shell style (Perl style)

• ① Single-line comment (C style), symbol: //

• ②Multi-line comment (C style), symbol: /* */

• ③Special single-line comments (not commonly used, Shell style), symbol:

<?php
echo "单行注释" ;//一般在代码右边少量说明或写在代码前面使之失效

echo "多行注释" ;
/*
一般说明脚本的相关信息，如版本，版权，作者日期等
使一长段代码失效
*/

echo "单行注释" ;#一般在代码右边少量说明或写在代码前面使之失效
?>

Description: Single-line comments only Comment to the end of the line or the current PHP code block (even if there is "?>" at the end of the line, it will not be commented. When PHP encounters "?>", it will jump out of PHP mode and then parse the HTML code or other)

4. Newline characters

Appropriately add newline indentation between statements to enhance the readability of the code

// 可读性较差
$name = 'PHP中文网'；echo $name;

// 适当加上换行可读性会更好
$name = 'PHP中文网';
echo $name;

5. Code segments (such as functions...)

function sum(int $a, int $b){
    // return意思是返回结果给调用者
    return ($a+$b);
}

// 执行，在客户端打印结果并输出
echo sum(10,20);

Recommended learning : "PHP Video Tutorial"

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