Characters not allowed in xml files

Some controls characters are also not allowed. See my answer below. Actually that's not quite true. A number of lower ascii characters are invalid also. If you try to write 0x03 to an Xml document you get an error typically and if you do manage to properly escape it into an XML document, most viewers will complain about the invalid character. Edge case but it does happen. This answer is absolutely wrong. Here is my XML exception with 0x12 illegal character 'System. XmlException: '', hexadecimal value 0x12, is an invalid character' — George.

It's also wrong in the other direction; as well as missing every single illegal character, the characters it does claim are illegal are perfectly legal, albeit with special meaning in the context. In fact even using a character entity for most control characters will cause an error when parsing. Show 8 more comments. Jon Senchyna 7, 2 2 gold badges 24 24 silver badges 45 45 bronze badges.

For Java, the regex pattern would be the same. And then you can use the method called replaceAll in the class String that expects a regex pattern as parameter. Check this: docs. I believe you cannot just put this pattern into a. NET regex constructor. A better implementation that takes care of the utf characters can be found here: stackoverflow. Show 1 more comment. These are not all invalid. By which I mean, only the characters in this specific range.

Other characters are not allowed. IsXmlChar ch. Since there are accepted uses for these two characters, they are not strictly speaking illegal XML characters. The less than and ampersand characters are two of the five pre-defined XML entities. The other three being the greater than symbol, the quote and the apostrophe, each of which are allowed in XML content without being expressed in entity notation.

XML processors are required to convert the pre-defined entites to their character representation without being defined anywhere in the XML document. Now that the meaning of what characters are illegal in XML has been clarified, let's move on to handling illegal characters when they do occur in an XML document.

A Google search for "remove illegal XML characters" results in plenty of code snippets. Most control characters are prohibited in XML: see the Specification for exact details.

There are also no reserved words as such in the user namespace of XML: you can call an element element and an attribute attribute and so on as in the following perverse example:. Check Legal Notices for details. See Figure 1. In the Find What box, enter the text for which you want to search.

Set other searching parameters, as desired. Click on Find Next. Select Replace option Regular Expression. Hit Replace All. Which special characters are not allowed in XML?

Category: technology and computing web design and html. Really, though, you should use a tool or library that writes XML for you and abstracts this kind of thing away for you so you don't have to worry about it. Can XML contain special characters?