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# html_entity_decode

(PHP 4 >= 4.3.0, PHP 5)

html_entity_decode -- Convert all HTML entities to their applicable characters

## Description

string html_entity_decode ( string string [, int quote_style [, string charset]] )

html_entity_decode() is the opposite of htmlentities() in that it converts all HTML entities to their applicable characters from string.

The optional second quote_style parameter lets you define what will be done with 'single' and "double" quotes. It takes on one of three constants with the default being `ENT_COMPAT`:

表格 1. Available quote_style constants

Constant Name | Description
--- | ---
`ENT_COMPAT` | Will convert double-quotes and leave single-quotes alone.
`ENT_QUOTES` | Will convert both double and single quotes.
`ENT_NOQUOTES` | Will leave both double and single quotes unconverted.

The ISO-8859-1 character set is used as default for the optional third charset. This defines the character set used in conversion.

PHP 4.3.0 及其后续版本支持如下字符集。

表格 2. 已支持字符集

字符集 | 别名 | 描述
--- | --- | ---
ISO-8859-1 | ISO8859-1 | 西欧，Latin-1
ISO-8859-15 | ISO8859-15 | 西欧，Latin-9。增加了 Latin-1（ISO-8859-1）中缺少的欧元符号、法国及芬兰字母。
UTF-8 |  | ASCII 兼容多字节 8-bit Unicode。
cp866 | ibm866, 866 | DOS-特有的 Cyrillic 字母字符集。PHP 4.3.2 开始支持该字符集。
cp1251 | Windows-1251, win-1251, 1251 | Windows-特有的 Cyrillic 字母字符集。PHP 4.3.2 开始支持该字符集。
cp1252 | Windows-1252, 1252 | Windows 对于西欧特有的字符集。
KOI8-R | koi8-ru, koi8r | 俄文。PHP 4.3.2 开始支持该字符集。
BIG5 | 950 | 繁体中文，主要用于中国台湾。
GB2312 | 936 | 简体中文，国际标准字符集。
BIG5-HKSCS |  | 繁体中文，Big5 的延伸，主要用于香港。
Shift_JIS | SJIS, 932 | 日文。
EUC-JP | EUCJP | 日文。

> 注: ISO-8859-1 将代替任何其它无法识别的字符集。

> 注: This function doesn't support multi-byte character sets in PHP < 5.

例子 1. Decoding HTML entities

`<?php
$orig = "I'll \"walk\" the <b>dog</b> now";
$a = htmlentities($orig);
$b = html_entity_decode($a);
echo $a; // I'll &quot;walk&quot; the &lt;b&gt;dog&lt;/b&gt; now
echo $b; // I'll "walk" the <b>dog</b> now
// For users prior to PHP 4.3.0 you may do this:
function unhtmlentities($string)
{
// replace numeric entities
$string = preg_replace('~&#x([0-9a-f]+);~ei', 'chr(hexdec("\\1"))', $string);
$string = preg_replace('~&#([0-9]+);~e', 'chr(\\1)', $string);
// replace literal entities
$trans_tbl = get_html_translation_table(HTML_ENTITIES);
$trans_tbl = array_flip($trans_tbl);
return strtr($string, $trans_tbl);
}
$c = unhtmlentities($a);
echo $c; // I'll "walk" the <b>dog</b> now
?>`

> 注: You might wonder why trim(html_entity_decode('&nbsp;')); doesn't reduce the string to an empty string, that's because the '&nbsp;' entity is not ASCII code 32 (which is stripped by trim()) but ASCII code 160 (0xa0) in the default ISO 8859-1 characterset.

See also htmlentities(), htmlspecialchars(), get_html_translation_table(), and urldecode().

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