Question

Im writing a python program using regex to find email addresses. re.findall function is giving wrong output whenever I try to use round brackets for grouping. Can anyone point out the mistake / suggest an alternate solution?

Here are two snippets of code to explain –

pat = "[\w]+[ ]*@[ ]*[\w]+.[\w]+"
re.findall(pat, '[e-mail] .rtrt.. [e-mail] ')

gives the output

['[e-mail]', '[e-mail]']

However, if I use grouping in this regex and modify the code as

pat = "[\w]+[ ]*@[ ]*[\w]+(.[\w]+)*"
re.findall(pat, '[e-mail] .rtrt.. [e-mail] ')

the output is

['.com', '.com']

To confirm the correctness of the regex, I tried this specific regex (in second example) in http://regexpal.com/ with the same input string, and both the email addresses are matched successfully.

Answer 1

In Python, re.findall returns the whole match only if there are no groups, if there are groups then it will return the groups. To get around this, you should use a non-capturing group (?:...). In this case:

pat = "[\w.]+ *@ *\w+(?:\.\w+)*"
re.findall(pat, '[e-mail] .rtrt.. [e-mail] ')