python: lower() german umlauts

Question

I have a problem with converting uppercase letters with umlauts to lowercase ones.

print("ÄÖÜAOU".lower())

The A, O and the U gets converted properly but the Ä,Ö and Ü stays uppercase. Any ideas?

First problem is fixed with the .decode('utf-8') but I still have a second one:

# -*- coding: utf-8 -*-
original_message="ÄÜ".decode('utf-8')
original_message=original_message.lower()
original_message=original_message.replace("ä", "x")
print(original_message)

Traceback (most recent call last): File "Untitled.py", line 4, in original_message=original_message.replace("ä", "x") UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 0: ordinal not in range(128)

Answer 1

You'll need to mark it as a unicode string unless you're working with plain ASCII;

> print(u"ÄÖÜAOU".lower())

äöüaou

It works the same when working with variables, it all depends on the type assigned to the variable to begin with.

> olle = "ÅÄÖABC"
> print(olle.lower())
ÅÄÖabc

> olle = u"ÅÄÖABC"
> print(olle.lower())
åäöabc

Answer 2

You are dealing with encoded strings, not with unicode text.

The .lower() method of byte strings can only deal with ASCII values. Decode your string to Unicode or use a unicode literal (u''), then lowercase:

>>> print u"\xc4AOU".lower()
äaou

Answer 3

If you're using Python 2 but don't want to prefix u"" on all your strings put this at the beginning of your program:

from __future__ import unicode_literals
olle = "ÅÄÖABC"
print(olle.lower())

will now return:

åäöabc

The encoding specifies how to interpret the characters read in from disk into a program, but the from __ future __ import statement tells how to interpret these strings within the program itself. You will probably need both.