How to convert characters into entities in php

<blockquote><p>php method to convert characters into entities: 1. Use the htmlentities() function to convert characters into HTML entities; 2. Use the htmlspecialchars() function to convert some predefined characters ("&" , "<", ">", etc.) into HTML entities. <!--”、“--></p></blockquote> <p><img src="https://img.php.cn/upload/article/000/000/024/6229b74393967375.jpg" alt="How to convert characters into entities in php" ></p> <p>The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer</p> <p><span style="font-size: 18px;"><strong>php Convert characters into entities</strong></span></p> <p><strong>1. Use the htmlentities() function</strong></p> <p>htmlentities() function to convert characters into HTML entities. </p> <p>Syntax:<br></p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">htmlentities(string,flags,character-set,double_encode)</pre><div class="contentsignin">Copy after login</div></div><table class="reference notranslate"><tbody><tr class="firstRow"><th width="20%">Parameters</th><th width="80%">Description</th></tr><tr><td><em> string</em></td><td>Required. Specifies the string to be converted. </td></tr><tr><td><em>flags</em></td><td> Optional. Specifies how to handle quotes, invalid encodings, and which document type to use. <p>Available quote types: </p><ul><li>ENT_COMPAT - Default. Only double quotes are encoded. </li><li>ENT_QUOTES - Encodes double and single quotes. </li><li>ENT_NOQUOTES - Do not encode any quotes. </li></ul><p>Invalid encoding: </p><ul><li>ENT_IGNORE - Ignore invalid encodings instead of having the function return an empty string. This should be avoided as this may have an impact on security. </li><li>ENT_SUBSTITUTE - Substitutes an invalid encoding with the specified character with the Unicode substitution character U FFFD (UTF-8) or &#FFFD; instead of returning an empty string. </li><li>ENT_DISALLOWED - <span lang="no-bok">Replace invalid code points in the specified document type with the Unicode replacement character U FFFD (UTF-8) or &#FFFD;. </span></li></ul><p>Additional flags specifying the document type to use: </p><ul><li>ENT_HTML401 - Default. Code processed as HTML 4.01. </li><li>ENT_HTML5 - Process code as HTML 5. </li><li>ENT_XML1 - Code processed as XML 1. </li><li>ENT_XHTML - Processing code as XHTML. </li></ul></td></tr><tr><td><em>character-set</em></td><td> Optional. A string specifying the character set to be used. <p> Allowed values: </p><ul><li>UTF-8 - Default. ASCII compatible multi-byte 8-bit Unicode</li><li>ISO-8859-1 - Western Europe</li><li>ISO-8859-15 - Western Europe (adds French and Finnish euro symbols missing from ISO-8859-1 Chinese letters) </li><li>cp866 - DOS-specific Cyrillic character set </li><li>cp1251 - Windows-specific Cyrillic character set </li><li>cp1252 - Windows-specific Western European character set </li><li>KOI8- R - Russian</li><li>BIG5 - Traditional Chinese, mainly used in Taiwan</li><li>GB2312 - Simplified Chinese, National Standard Character Set</li><li>BIG5-HKSCS - Big5## with Hong Kong extension </li>#Shift_JIS - Japanese <li></li>EUC-JP - Japanese <li></li>MacRoman - Character set used by Mac operating systems <li></li></ul><p>Comments: <strong> In versions prior to PHP 5.4, unrecognized character sets were ignored and replaced by ISO-8859-1. As of PHP 5.4, unrecognized character sets are ignored and replaced by UTF-8. </strong></p></td></tr><tr><td>double_encode<em></em></td> Optional. A Boolean value that specifies whether to encode existing HTML entities. <td><ul>TRUE - Default. Each entity will be converted. <li></li>FALSE - Existing HTML entities will not be encoded. <li></li></ul></td></tr></tbody><p>示例：通过使用西欧字符集，把一些字符转换为 HTML 实体：</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"><?php $str = "My name is Øyvind Åsane. I'm Norwegian."; echo htmlentities($str, ENT_QUOTES, "ISO-8859-1"); // Will only convert double quotes (not single quotes), and uses the character-set Western European ?></pre><div class="contentsignin">Copy after login</div></div><p>上面代码的 HTML 输出如下（查看源代码）：</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"><!DOCTYPE html> <html> <body> My name is Øyvind Åsane. I'm Norwegian. </body> </html></pre><div class="contentsignin">Copy after login</div></div><p>上面代码的浏览器输出如下：</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">My name is Øyvind Åsane. I'm Norwegian.</pre><div class="contentsignin">Copy after login</div></div><p><strong>2、使用htmlspecialchars()函数</strong></p><p>htmlspecialchars() 函数把一些预定义的字符转换为 HTML 实体。</p><p>预定义的字符是：</p><ul style="list-style-type: disc;"><li><p><code>& </code>（和号）成为 <code>&</code></p></li><li><p><code>"</code> （双引号）成为 <code>"</code></p></li><li><p><code>'</code> （单引号）成为 <code>'</code></p></li><li><p><code><</code> （小于）成为 <code><</code></p></li><li><p><code>></code> （大于）成为 <code>></code></p></li></ul><p>语法：</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">htmlspecialchars(string,flags,character-set,double_encode)</pre><div class="contentsignin">Copy after login</div></div><table class="reference"><tbody><tr class="firstRow"><th width="20%">参数</th><th width="80%">描述</th></tr><tr><td><em>string</em></td><td>必需。规定要转换的字符串。</td></tr><tr><td><em>flags</em></td><td>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。<p>可用的引号类型：</p><ul><li>ENT_COMPAT - 默认。仅编码双引号。</li><li>ENT_QUOTES - 编码双引号和单引号。</li><li>ENT_NOQUOTES - 不编码任何引号。</li></ul><p>无效的编码：</p><ul><li>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。</li><li>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。</li><li>ENT_DISALLOWED - <span lang="no-bok">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;。</span></li></ul><p>规定使用的文档类型的附加 flags：</p><ul><li>ENT_HTML401 - 默认。作为 HTML 4.01 处理代码。</li><li>ENT_HTML5 - 作为 HTML 5 处理代码。</li><li>ENT_XML1 - 作为 XML 1 处理代码。</li><li>ENT_XHTML - 作为 XHTML 处理代码。</li></ul></td></tr><tr><td><em>character-set</em></td><td>可选。一个规定了要使用的字符集的字符串。<p>允许的值：</p><ul><li>UTF-8 - 默认。ASCII 兼容多字节的 8 位 Unicode</li><li>ISO-8859-1 - 西欧</li><li>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）</li><li>cp866 - DOS 专用 Cyrillic 字符集</li><li>cp1251 - Windows 专用 Cyrillic 字符集</li><li>cp1252 - Windows 专用西欧字符集</li><li>KOI8-R - 俄语</li><li>BIG5 - 繁体中文，主要在台湾使用</li><li>GB2312 - 简体中文，国家标准字符集</li><li>BIG5-HKSCS - 带香港扩展的 Big5</li><li>Shift_JIS - 日语</li><li>EUC-JP - 日语</li><li>MacRoman - Mac 操作系统使用的字符集</li></ul><p><strong>注释：</strong>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。</p></td></tr><tr><td><em>double_encode</em></td><td>可选。一个规定了是否编码已存在的 HTML 实体的布尔值。<ul><li>TRUE - 默认。将对每个实体进行转换。</li><li>FALSE - 不会对已存在的 HTML 实体进行编码。</li></ul></td></tr></tbody></table><p>返回值：：</p><ul style="list-style-type: disc;"><li><p>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。 </p></li></ul><p>示例：把一些预定义的字符转换为 HTML 实体</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false"><?php $str = "Jane & 'Tarzan'"; echo htmlspecialchars($str, ENT_COMPAT); // 默认，仅编码双引号 echo "<br>"; echo htmlspecialchars($str, ENT_QUOTES); // 编码双引号和单引号 echo "<br>"; echo htmlspecialchars($str, ENT_NOQUOTES); // 不编码任何引号 ?></pre><div class="contentsignin">Copy after login</div></div><p>输出结果：</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">Jane & 'Tarzan' Jane & 'Tarzan' Jane & 'Tarzan'</pre><div class="contentsignin">Copy after login</div></div><p>推荐学习：《<a href="https://www.php.cn/course/list/29/type/2.html" target="_blank">PHP视频教程</a>》</p>

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