What are PHP tags? Four styles of PHP markup

When parsing a file, PHP looks for start and end tags, namely , which tell PHP to start and stop parsing the code in between. This parsing method allows PHP to be embedded in various documents, and any part other than the opening and closing tags will be ignored by the PHP parser.

PHP also allows the use of the short tags , but their use is discouraged. Short tags can only be used by activating the short_open_tag configuration directive in php.ini or using the configuration option --enable-short-tags when compiling PHP.

If the file content is pure PHP code, it is best to remove the PHP closing tag at the end of the file. This prevents PHP from accidentally adding spaces or newlines after the closing tag, causing PHP to start outputting these spaces when there is no intention to output them in the script.

<?php
echo  "Hello world" ;
// ... more code
echo  "Last statement" ;
// 脚本至此结束，并无 PHP 结束标记

Introduction to the 4 markup styles in php

1.xml style (standard style is recommended)

<?php 
echo"这是xml风格的标记"; 
?>

xml style markup is commonly used The tag is also a recommended tag and cannot be disabled by the server. This style of tag can be used in xml and xhtml.

2. Script style

<script languange="php"> 
echo&#39;这是脚本风格的标记&#39;; 
</script>

3. Short style

<?这是简短风格的标记;?>

Note: short _open_tag=on needs to be set in php.ini, the default is on, or Added –enable-short-tags option when compiling PHP. (PHP 3 version can also activate the use of short tags through the short_tags() function.)
4.asp style

<% 
echo&#39;这是asp风格的标记&#39;; 
%>

Note: Need to be in the php.ini configuration file Turn on asp_tags = on;

The above asp style and short style need to be set in php.ini. Not supported by default.

Note: Support for ASP style tags was added in version 3.0.4.

Note: Avoid using short tags in the following situations: developing programs or libraries that need to be distributed, or developing on servers that are not controlled by the user. Because the target server may not support short tags. For code portability and distribution, make sure not to use short tags.

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