java - regex about duplicate words

Asked Sep 05 '17 at 09:25

Active Sep 05 '17 at 09:25

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So, this regex means duplicate words: "\b(\w+)(\s+\1\b)+"

but what does the '+' do after the '\w'? Wouldn't it still identify duplicate words without the '+'? Since the second parenthesis/group is the one identifying any repeats of the previous word.

asked Sep 05 '17 at 09:25

Kerage Chan

`\w` matches 1 letter/digit/`_`. `\w+` matches **one or more** such chars. – Wiktor Stribiżew Sep 05 '17 at 09:27
omg thank you, \\w is actually a LETTER(or digit) not the full WORD – Kerage Chan Sep 05 '17 at 09:40
Yes, just Google about *quantifiers*. – Wiktor Stribiżew Sep 05 '17 at 09:40
1

Have a look at http://regexr.com/. They provide a nice overview about regex usage, and you can test your expressions pretty nicely. – PixelMaster Sep 05 '17 at 10:10

java - regex about duplicate words

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