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Python Regular Expressions in Python Introduction to Regular Expressions Sets

Sahar Nasiri
Sahar Nasiri
7,454 Points

Can we use "?" as a optional character

All the characters in the [] could exist or not, can't we write the print line like this:

print(re.findall(r'[-?\w?\d?+?.?]@[-?\w?\d?.?]', data))

1 Answer

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

Square brackets [] define a character class (or set). Repeating letters within the brackets are redundant. Putting the question mark inside the class makes it also an optional character of the class. Without a question mark outside the class (and no other +, * or ? modifier) means exactly one character of the class.

So your proposed pattern would only find a single character followed by a @ followed by another single character.