PHP中htmlentities跟htmlspecialchars的区别

htmlentities跟htmlspecialchars都是用于将字符串的特殊字符中转成HTML字符实体。只是htmlspecialcharsl转义的特殊字符集只有5个，

'&' (ampersand) =>'&'
'"' (double quote) =>'"' when ENT_NOQUOTES is not set.
''' (single quote) =>''' only when ENT_QUOTES is set.
'<' (less than) =>'&lt;'
'>' (greater than) =>'&gt;'

而htmlentities转义的特殊字符集是完整的HTML字符实体集。

对于这两个函数，php手册上都是英文做的解释，其中在htmlentities函数的说明部分有这么一段英文：

This function is identical(完全相同的) to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents(HTML character entity equivalents译为HTML字符实体等价物) are translated into these entities.

从这句话中我们也可以看出来这两个函数虽然基本功能差不多，但是还是有细微的差别在里面的。再仔细看htmlspecialchars函数里面的一段话：

Certain characters(其实就是'&', 双引号(没有设置ENT_NOQUOTES时才会转义), 单引号(当且仅当设置ENT_QUOTES才会转义), '<', '>') 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.

注：使用这两个函数时最后指明编码格式哦。

参考链接

1. W3Schools.com - Symbols Entities
2. 这是一个完整的字符实体参考Webstandards.org - Symbol Entities
3. http://www.neoease.com/using-html-symbol-entities/