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Editorial Team
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Asked: 2026-05-16T15:33:48+00:00

Sometimes the string values of Properties in my Classes become odd. They contain illegal

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Sometimes the string values of Properties in my Classes become odd. They contain illegal characters and are displayed like this (with boxes):

123[]45[]6789

I’m assuming those are illegal/unrecognized characters. I serialize all my objects to XML and then upload them via Web Service. When I retrieve them again, some characters are replaced with oddities. This happens most often with hyphens and dashes that have been typed using Word. Is that the cause of it?

Is there anyway I can check to see if the string contains any of these unrecognized characters via regex or something?

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1 Answer

  1. Editorial Team

    The first thing to remember, is that there is no such thing as a “special character” or an “illegal character”. There are characters that are special in certain circumstances, there are non-characters, but there are no generally “special characters” or “illegal characters”.

    What you have here is either:

    1. Perfectly normal characters for which your font doesn’t have a glyph.
    2. Perfectly normal characters that aren’t printable (e.g. control characters).
    3. An artefact of how the debugger works.

    The first thing is to find out what that character is. Find the integer value of the character, and then look it up.

    An important one to look out for is U+FFFD (�) as it is sometimes used when a decoder has recieved a bunch of bytes that make no sense in the context of the encoding it is trying to use (e.g. 0x80 followed by 0x20 makes no sense in UTF-8, and one possible response is to use U+FFFD as a “something strange here” marker, other possible responses are throwing an error, and also silently ignoring the error or trying to guess at intent though those last two bring security issues).

    Once you’ve this figured out, you can begin to reason about why it’s getting in there if it isn’t expected. Could it be an ecoding issue (charset written in is not the charset read in)? Could it be actually intended to be there? Could it be something else? You can’t begin to answer that until you have more information on the bug.

    Finally, there’s the matter of what to do about it. This will hopefully be obvious from the answers you’ve found in your research above. Possibly the answer will be “nothing it’s fine”, possibly something simple or something hard. Can’t say yet.

    Do not just filter with a regular expression. Maybe that will turn out to be the correct solution, but you don’t know yet, so maybe you’re making a deeper bug harder to find than it is now, or damaging perfectly good data.

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