filter out html tag in user input using validator

[Ningfeng Xu]

hi, how can I filter out html tag in user input in validator?

I used the following code(this code actually is for the opposite case, say, true if the input has "<xxx>" substring. The reason is so far I don't know how to write the desired regular expression, "not-<xxx>"):

<var><var-name>mask</var-name><var-value>^<[^<>]+>$</var-value></var>

But the validator reports error, saying this is not well-formatted. I know the problem is "<" in "<[^<>]+>". I tried the unicode of "<", as the following, no error reported any more, but still not working(can't validate true if input has html tag:
<var><var-name>mask</var-name><var-value>^\u003c[^\u003c>]+>$</var-value></var>

Any one can help?

Thanks.

[Ningfeng Xu]

I solved this issue, as the following:

<![CDATA[ ^[^<]*[^>]*$ ]]>

This is not a strong solution, to detect html tags in user input, but so far good enough for me.