[xml] How can I escape double quotes in XML attributes values?

From the following trials

<tag attr="\"">
<tag attr="<![CDATA["]]>">
<tag attr='"'>

Only the last one works for an XML parser that I'm using here. Is there an alternative?

From the XML specification:

To allow attribute values to contain both single and double quotes, the apostrophe or single-quote character (') may be represented as "'", and the double-quote character (") as """.

A double quote character (") can be escaped as ", but here's the rest of the story...

Double quote character must be escaped in this context:

• In XML attributes delimited by double quotes:

  <EscapeNeeded name="Pete &quot;Maverick&quot; Mitchell"/>
  

Double quote character need not be escaped in most contexts:

• In XML textual content:

  <NoEscapeNeeded>He said, "Don't quote me."</NoEscapeNeeded>
  

• In XML attributes delimited by single quotes ('):

  <NoEscapeNeeded name='Pete "Maverick" Mitchell'/>
  

  Similarly, (') require no escaping if (") are used for the attribute value delimiters:

  <NoEscapeNeeded name="Pete 'Maverick' Mitchell"/>
  

See also

• Simplified XML Escaping

The String conversion page on the Coder's Toolbox site is handy for encoding more than a small amount of HTML or XML code for inclusion as a value in an XML element.