Re: How to test if a string is unicode string?

[cavac]

Technically, there are any number of ways to check if the string in Perl has bytes with a number greater than 255 or 127.

You can check if bytes > 127 exists, which is outside the standard ASCII range. This may indicate some sort of Unicode or UTF encoded string. Or it may indicate some "extended ASCII" encoding where characters 128-255 represent some language/area specific encoding like german Umlauts or spanish punctuations (żĄ) or DOS "graphical" symbols. Or it may indicate binary data.

It's noteworthy that UTF8 encodes data by setting the highest bit in a byte, but Unicode also uses the range 128-255 for symbols.

So, there is no absolutely foolproof way to guess if you got Unicode, UTF-encoded stuff or some other data (either encoded or not). This is all rather unfortunate and can be a huge pain in the buttocks (speaking from experience). You basically have to track that yourself in your program alongside your data.

See also:

• The "Unicode Bug" in perldoc
• How to know if a string has UTF-8?
• Am I using utf8::is_utf8 correctly? on stackoverflow
• Handling of legacy encodings in perldoc

[harangzsolt33]

Hmm... Interesting. Thank you!