utf-8 plus question marks

I have a site that displays user input by decoding it to unicode using utf-8. However, user input can includ开发者_StackOverflow中文版e binary data, which is obviously not always able to be 'decoded' by utf-8.

I'm using Python, and I get an error saying:

'utf8' codec can't decode byte 0xbf in position 0: unexpected code byte. You passed in '\xbf\xcd...

Is there a standard efficient way to convert those undecodable characters into question marks?

It would be most helpful if the answer uses Python.

Try:

inputstring.decode("utf8", "replace")

See here for reference

I think what you are looking for is:

str.decode('utf8','ignore')

which should drop invalid bytes rather than raising exception