Can't use unichr in Python 3.1

I've been looking through the Python Cookbook (2nd Edition) to learn how to process strings and characters.

I wanted to try converting a number into its Unicode equivalent. So I tried using the built-in function called 'unichr', which, according to the Cookbook, goes something like:

>>> print repr(unichr(8224))

... and will output:

u'\u2020'

However, the code failed. I thought it had something to do with print (because Python 3 uses print() instead of print ""), but that didn't work out as well. I tried several variations to the code, and it still failed. At long last, I just typed a simple line:

unichr(10000)

To my surprise, this error message kept popping up, no matter what value I put into the above function:

 NameError: name 'unichr' is not defined

What could be the problem? Is there some specific module that I'm supposed to import?

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最佳答案

In Python 3, you just use chr:

>>> chr(10000)
'✐'

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Python 3.x doesn't have a special Unicode string type/class. Every string is a Unicode string. So... I'd try chr. Should give you what unichr did pre-3.x. Can't test, sadly.

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In Python 3, there's no difference between unicode and normal strings anymore. Only between unicode strings and binary data. So the developers finally removed the unichr function in favor of a common chr which now does what the old unichr did. See the documentation here.

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In case you need to run in both python 2 and python 3, you can use this common syntax (the unused syntax would point to the new one)

try:
unichr
except NameError:
unichr = chr

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As suggestted by this is a better way to do it for it is compatible for both 2 and 3:

# Python 2 and 3:
from builtins import chr
assert chr(8364) == '€'

And you may need pip install future incase some error occures.