Why do regular expressions work this way?

Question

Regular Expressions

In python reg. expressions work correctly, for example:

import re
s = '''Если ты хочешь построить корабль, не надо созывать людей, планировать, делить работу, доставать инструменты. 
Надо заразить людей стремлением к бесконечному морю. Тогда они сами построят корабль.'''
pattern = r'\w+'
match = re.findall(pattern, s)
if match:
    print(match)

Outputs as expected:
['If', 'you', 'want', 'build', 'ship', 'don't', 'must', 'convene', 'people', 'plan', 'share', 'work ', 'get', 'tools', 'Need', 'infect', 'people', 'desire', 'to', 'endless', 'sea', 'Then', 'they', 'themselves', 'will build', 'ship']

I do the same in the program, the output is the devil knows what:
\w [a-z0-9] Letters and numbers

Can't see any letters or words at all.
Change to capital W
\W [^a-z0-9] In addition to letters and numbers

, A sees both letters and numbers here. What's wrong?

Answer 1

pcre.org/original/doc/html/pcrepattern.html#SEC2

Unicode property support
Another special sequence that may appear at the start of a pattern is (*UCP). This has the same effect as setting the PCRE_UCP option: it causes sequences such as \d and \w to use Unicode properties to determine character types, instead of recognizing only characters with codes less than 128 via a lookup table.

To \wmatch not only with the Latin alphabet, you need to add (*UCP).
(*UCP)\w+

Answer 2

in a programme

And what kind of program is this, and who wrote the implementation of regular expressions in it?
To the author and questions.