in a python 3 string from another program, ü is two characters, the u and the umlaut. Why?

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I am taking a string from a php 7 program, and processing it in Python 3.7.2.

my_str = 'ü'

print(type(my_str))

str_list = list(my_str)

for letter in str_list:
    print('letter',letter)

if 'ü' in my_str:
    print('we have the umlaut')
else:
    print('we have no umlaut')

Here is the output:

<class 'str'>
letter u
letter ̈
we have no umlaut

Why is the letter u separate from the umlaut? If I type a ü in this string, it is read as 'ü', and the test for 'ü' succeeds. How can I correct this string, so it has a ü and not two separate characters?

Thanks in advance for any tips. I have searched for this and found nothing helpful.

diacritics character-encoding python
1 Answers

The character in your string and the one in your condition have different representations:

from unicodedata import name, normalize


my_str = 'ü'
for c in my_str:
    print(name(c))

# LATIN SMALL LETTER U
# COMBINING DIAERESIS

your_u = 'ü'  # copy pasted from your 'if ...' line
for c in your_u:
    print(name(c))

# LATIN SMALL LETTER U WITH DIAERESIS

You can normalize your string:

my_normalized_str = normalize('NFC', my_str)

for c in my_normalized_str:
    print(name(c))

#LATIN SMALL LETTER U WITH DIAERESIS

And now your comparison will work as expected:

if 'ü' in my_normalized_str:
    print('we have the umlaut')
else:
    print('we have no umlaut')

# we have the umlaut
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