html_entity_decode

功能：html解码，把html标签按照源码格式，浏览器进行解析。

反函数是：htmlentities() ，功能是把html标签按照字符的形式显示出来，浏览器不解析。

(PHP 4 >= 4.3.0, PHP 5)

html_entity_decode — Convert all HTML entities to their applicable characters

 

htmlspecialchars_decode

功能：html解码，把html标签按照源码格式解析。

反函数是：htmlspecialchars()，功能是把html标签按照字符的形式显示出来，浏览器不解析。

(PHP 5 >= 5.1.0)

 

htmlspecialchars_decode — Convert special HTML entities back to characters

名称	html_entity_decode	htmlspecialchars_decode
定义	Convert all HTML entities to their applicable characters	Convert special HTML entities back to characters
使用版本	(PHP 4 >= 4.3.0, PHP 5)	(PHP 5 >= 5.1.0)
参数	( string $string [, int $flags = ENT_COMPAT | ENT_HTML401 [,string $encoding = ‘UTF-8’ ]] )	( string $string [, int$flags = ENT_COMPAT | ENT_HTML401 ] )

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From the PHP documentation for htmlentities:

This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

From the PHP documentation for htmlspecialchars:

Certain characters have special significance in HTML, and should be represented by HTML entities if they are to preserve their meanings. This function returns a string with some of these conversions made; the translations made are those most useful for everyday web programming. If you require all HTML character entities to be translated, use htmlentities() instead.

The difference is what gets encoded. The choices are everything (entities) or “special” characters, like ampersand, double and single quotes, less than, and greater than (specialchars).

 

I prefer to use htmlspecialchars whenever possible.

结论：htmlentities 和 htmlspecialchars 的区别在于 htmlentities 会转化所有的 html character entity，而htmlspecialchars 只会转化手册上列出的几个 html character entity （也就是会影响 html 解析的那几个基本字符）。一般来说，使用 htmlspecialchars 转化掉基本字符就已经足够了，没有必要使用 htmlentities。实在要使用 htmlentities 时，要注意为第三个参数传递正确的编码。