What I think in addition to what Atkinso writes: If you just strip arbitrary bytes that happen to be equal in value to the numeric value of ASCII control characters or whitespace, how can you be sure that you don’t destroy valid non-whitespace unicode symbols?
You can’t! This will work only of you have actually ASCII input.
No, the filter is correct even for UTF-8. Any ASCII character is exactly unchanged in UTF-8 (part of the reason it is popular). Since this code only filters out ASCII characters it works fine with ASCII or UTF-8.
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