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) >>> str = '42' >>> reg.search(st...">
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Python - regex Why does `findall` find nothing but` search` works?

>>> reg = re.compile(r'^\d{1,3}(,\d{3})*$')
>>> str = '42'
>>> reg.search(str).group()
'42'
>>> reg.findall(str)
['']
>>>

python regex Why reg.findalldoesn't it find anything, but reg.searchworks in this code snippet above?

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When you have capture groups (wrapped with parentheses) in the regular expression, it findallwill return a match for the captured group; And in your case, the captured group corresponds to an empty string; You can do this without grabbing with ?:if you want to return the entire match; re.searchignores capture groups, on the other hand. They are reflected in the documentation:

re.findall:

, . , . , ; , .

re.search:

, , MatchObject. , ; , - .

import re
reg = re.compile(r'^\d{1,3}(?:,\d{3})*$')
s = '42'
reg.search(s).group()
​# '42'

reg.findall(s)
# ['42']
+5

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