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PHP's function htmlentities() that converts strings into html entities

黄舟

Nov 02, 2017 am 11:20 AM

htmlphpstring

实例

把一些字符转换为 HTML 实体：

<?php
$str = "<© W3CSçh°°¦§>";
echo htmlentities($str);
?>

上面代码的 HTML 输出如下（查看源代码）：

<!DOCTYPE html>
<html>
<body>
<&copy; W3CS&ccedil;h&deg;&deg;&brvbar;&sect;>
</body>
</html>

上面代码的浏览器输出如下：

<© W3CSçh°°¦§>

定义和用法

htmlentities() 函数把字符转换为 HTML 实体。

提示：要把 HTML 实体转换回字符，请使用 html_entity_decode() 函数。

提示：请使用 get_html_translation_table() 函数来返回 htmlentities() 使用的翻译表。

语法

htmlentities(string,flags,character-set,double_encode)

参数	描述
string	必需。规定要转换的字符串。
flags	可选。规定如何处理引号、无效的编码以及使用哪种文档类型。可用的引号类型： ENT_COMPAT - 默认。仅编码双引号。 ENT_QUOTES - 编码双引号和单引号。 ENT_NOQUOTES - 不编码任何引号。无效的编码： ENT_IGNORE - 忽略无效的编码，而不是让函数返回一个空的字符串。应尽量避免，因为这可能对安全性有影响。 ENT_SUBSTITUTE - 把无效的编码替代成一个指定的带有 Unicode 替代字符 U+FFFD（UTF-8）或者 FFFD; 的字符，而不是返回一个空的字符串。 ENT_DISALLOWED - 把指定文档类型中的无效代码点替代成 Unicode 替代字符 U+FFFD（UTF-8）或者 FFFD;。规定使用的文档类型的附加 flags： ENT_HTML401 - 默认。作为 HTML 4.01 处理代码。 ENT_HTML5 - 作为 HTML 5 处理代码。 ENT_XML1 - 作为 XML 1 处理代码。 ENT_XHTML - 作为 XHTML 处理代码。
character-set	可选。一个规定了要使用的字符集的字符串。允许的值： UTF-8 - 默认。ASCII 兼容多字节的 8 位 Unicode ISO-8859-1 - 西欧 ISO-8859-15 - 西欧（加入欧元符号 + ISO-8859-1 中丢失的法语和芬兰语字母） cp866 - DOS 专用 Cyrillic 字符集 cp1251 - Windows 专用 Cyrillic 字符集 cp1252 - Windows 专用西欧字符集 KOI8-R - 俄语 BIG5 - 繁体中文，主要在台湾使用 GB2312 - 简体中文，国家标准字符集 BIG5-HKSCS - 带香港扩展的 Big5 Shift_JIS - 日语 EUC-JP - 日语 MacRoman - Mac 操作系统使用的字符集注释：在 PHP 5.4 之前的版本，无法被识别的字符集将被忽略并由 ISO-8859-1 替代。自 PHP 5.4 起，无法被识别的字符集将被忽略并由 UTF-8 替代。
double_encode	可选。一个规定了是否编码已存在的 HTML 实体的布尔值。 TRUE - 默认。将对每个实体进行转换。 FALSE - 不会对已存在的 HTML 实体进行编码。

技术细节

返回值：	返回已转换的字符串。如果 string 包含无效的编码，则返回一个空的字符串，除非设置了 ENT_IGNORE 或者 ENT_SUBSTITUTE 标志。
PHP 版本：	4+
更新日志：	在 PHP 5 中，character-set 参数的默认值改为 UTF-8。在 PHP 5.4 中，新增了：ENT_SUBSTITUTE、ENT_DISALLOWED、ENT_HTML401、ENT_HTML5、ENT_XML1 和 ENT_XHTML。在 PHP 5.3 中，新增了 ENT_IGNORE。在 PHP 5.2.3 中，新增了 double_encode 参数。在 PHP 4.1 中，新增了 character-set 参数。

更多实例

实例 1

把一些字符转换为 HTML 实体：

<?php
$str = "Jane & &#39;Tarzan&#39;";
echo htmlentities($str, ENT_COMPAT); // Will only convert double quotes
echo "<br>";
echo htmlentities($str, ENT_QUOTES); // Converts double and single quotes
echo "<br>";
echo htmlentities($str, ENT_NOQUOTES); // Does not convert any quotes
?>

上面代码的 HTML 输出如下（查看源代码）：

<!DOCTYPE html>
<html>
<body>
Jane & &#39;Tarzan&#39;<br>
Jane & &#039;Tarzan&#039;<br>
Jane & &#39;Tarzan&#39;
</body>
</html>

上面代码的浏览器输出如下：

Jane & &#39;Tarzan&#39;
Jane & &#39;Tarzan&#39;
Jane & &#39;Tarzan&#39;

实例 2

通过使用西欧字符集，把一些字符转换为 HTML 实体：

<?php
$str = "My name is Øyvind Åsane. I&#39;m Norwegian.";
echo htmlentities($str, ENT_QUOTES, "ISO-8859-1"); // Will only convert double quotes (not single quotes), and uses the character-set Western European
?>

上面代码的 HTML 输出如下（查看源代码）：

<!DOCTYPE html>
<html>
<body>
My name is &Oslash;yvind &Aring;sane. I&#039;m Norwegian.
</body>
</html>

上面代码的浏览器输出如下：

My name is Øyvind Åsane. I&#39;m Norwegian.

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