How can I include an ampersand (&) character in an XML document?

问题

How can I put an & symbol in an attribute of an XML tag while keeping the XML valid?

<?xml version="1.0" ?> 
<a text="b&c"/>

When I use W3School's validator, I get the error:

EntityRef: expecting ';'

回答1:

Use a character reference to represent it: &

See the specification:

The ampersand character (&) and the left angle bracket (<) MUST NOT appear in their literal form, except when used as markup delimiters, or within a comment, a processing instruction, or a CDATA section. If they are needed elsewhere, they MUST be escaped using either numeric character references or the strings " & " and " < " respectively. The right angle bracket (>) may be represented using the string " > ", and MUST, for compatibility, be escaped using either " > " or a character reference when it appears in the string " ]]> " in content, when that string is not marking the end of a CDATA section.

回答2:

You can use these escape sequences :

< (less-than)                   -   &#60; or &lt;

> (greater-than)                -   &#62; or  &gt;

& (ampersand)                   -   &#38;

' (apostrophe or single quote)  -   &#39;

" (double-quote)                -   &#34;

来源：https://stackoverflow.com/questions/14500800/how-can-i-include-an-ampersand-character-in-an-xml-document