What are the comment symbols not allowed in PHP?

The comment symbol not allowed in PHP is "quote"; there are two types of comments in PHP, namely single-line comments and multi-line comments. There are two ways to declare single-line comments, namely using "# ” and backslash “//”, while multi-line comments use /* */ symbols.

#The operating environment of this article: Windows7 system, PHP7.1, Dell G3 computer.

What are the comment symbols not allowed by PHP?

The comment symbols not allowed by PHP are D and '.

A, //
B,
#C, /* */
D, '

There are two types of comments in PHP, which are single lines. Comments and multiline comments.

1. Single-line comments

Each line must be marked with a separate comment, which is called a single-line comment. It is used for brief description. There are two ways to declare a single-line comment, using "#" and backslash "//".

The sample code is as follows:

<?php
    #这是第一行注释
    echo "PHP中文网<br>";
    //这是第二行注释
    echo "https://www.php.cn";
    // echo "PHP 注释";
?>

In the above code example, the second line uses "#" to define a comment, and the fourth and sixth lines use "// ” defines an annotation.

The running results are as follows:

PHP中文网
https://www.php.cn

Tip: The most widely used single-line comment is to use double slashes "//" to define the comment.

2. Multi-line comments

Multi-line comments are used to comment on multi-line content, and are often used for comments on multi-line text. The content of the comment needs to be contained in (/* and */), starting with "/*" and ending with "*/".

Tip: Multi-line comments cannot be nested within each other.

The sample code is as follows:

<?php
    /*
        这是一个多行注释
        输出网站名称及链接地址
    */
    echo "PHP中文网<br>";
    echo "https://www.php.cn";
    /* echo "PHP 注释"; */
?>

The running results are as follows:

https://www.php.cn

Multi-line comments are often used by developers to introduce the functions and parameters of a function or method. In addition, it should be noted that multi-line comments are composed of two tags, "/*" and "*/". It will not work if you ignore either one.

Recommended learning: "PHP Video Tutorial"

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