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Re: How can I tell if a string contains binary data or plain-old text?

by dakkar (Hermit)
on Oct 31, 2003 at 14:43 UTC ( #303553=note: print w/replies, xml ) Need Help??

in reply to How can I tell if a string contains binary data or plain-old text?

First of all: you can't have a "Unicode" file.

You can have a file containing Unicode code-points encoded in one of the transformation formats defined by the Unicode standard, such as UTF-8 or UTF-16.

So the question becomes:

I have a byte-stream. Is it a valid (ISO-8859-1|UTF-8|UTF-16)-encoded representation of some text?

This can be answered, since none of those encodings defines a meaning for each and every byte-sequence. But this is quite possibly not the answer you're looking for.

The way I see it, it's easier to check if your byte-stream contains something you know not to be text, using something like file(2) or File::MMagic as already suggested.

Doing it the other way ("is it a valid encoded form") gives you a lot of "this is text" when, in fact, it is nothing intelligible.

You could try to decode it and then do some heuristics to see if looks like text (ex. a lot of letters from the same script/writing system in a row, or something of the sort), but I think it's more trouble than it's worth.

        dakkar - Mobilis in mobile

Most of my code is tested...

Perl is strongly typed, it just has very few types (Dan)

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[perldigious]: 1nickt: No more red meat! It would be more humane to just kill you, wouldn't it! :-)
[1nickt]: Just don't make it barf.
[1nickt]: perldigious that's exactly what my stepson says.
[1nickt]: the tick that can make you a vegetarian
[perldigious]: Your Mother: Yeah, I have a tool for ticks that I use (mostly on my dogs thankfully), but it's just a cheapo one I got from my vets office... it works pretty good though.
erix saw a tick in a natural history museum collected from the scrotum of the curator (it was removed)
[Your Mother]: The exhibit, the tick, or the scrotum?
[erix]: (the man is even a paleontologist )
[1nickt]: erix unfortunately that's there favourite spot. That's why they are usually spotted crawling *up* your leg.
[erix]: ha, the tick and, as it happens, also the curator (now a professor of Paleont.)

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