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Is the early example in the document correct?

Using an input string of abc123 he claims [a-z]+\d+ will match the entire string (which I agree with). He then says that [a-z]+?\d+? will only match abc1. Wouldn't it fail since the non-greedy match on [a-z] would just match 'a' causing the non-greedy match on \d to fail trying to match 'b'?

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no it'll still match but because both are non-greedy it could match on just c1 instead of abc123.

It could match on c1, but I believe since most (all?) regex parsers parse left-to-right, it will match the a, look for another a-z character or a digit, find b, repeat, find c, then find 1 which completes the pattern.

http://regex101.com/r/aR5xM2

I used this tester posted elsewhere in the thread, it seems like since the lazy components expand "as needed" to achieve a match, it will succeed on "abc1".

EDIT: I wrapped it in a group for clarity.

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