python regex：re.findall（）的行为与预期不符

Question

I have the following code:

testREString = '(hello | goodbye) \s darkness \s my \s old \s friend'
testString = 'sound of silence: goodbye darkness my old friend'
exp = re.compile(testREString, re.VERBOSE)
print(exp.findall(testString))

and it returns: ['goodbye'] where I had expected it to return the full sentence - in fact, using exp.search(testString) it had picked out the rest of the sentence correctly. Why then, was the complete match not displayed?

Thank you for your time.

Answer 1

(...) in a regular expression defines a capturing group.

re.findall returns the content of the capturing groups if your expression defines any.

You can make it a non-capturing group (?:hello|goodbye) to avoid this. See What is a non-capturing group?

Answer 2

khelwood has explained why findall() behaves this way. If you want to catch the whole match without changing the regex, use

exp.group(0)