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Regex Crossword

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Re: Regex Crossword

#111

Post by jplahn »

karma89 wrote: post #110
jplahn wrote: post #80

Earlier quoted context omitted.

It begs the question, do you mean Facebook the social network, or Facebook the company? Because there are surely many benefits coming from the company that don't necessarily depend on the social network.

It's hard to imagine one existing without the other

I think one existing without the other could certainly be the case in the nearish future. Not everything they're doing is tied into the Facebook site.

Re: Regex Crossword

#112

Post by takeda »

toastedzergling wrote: post #102
mgraczyk wrote: post #64

Earlier quoted context omitted.

That isn't how the Kleene star works. A* is "the set of all strings over the alphabet {A}, including the empty string ε." "QQQQ" is not a string over the alphabet {A} because it contains the symbol 'Q', which is not in {A}.

I have no idea what you're talking about. My point is more pragmatic the regex /A / will match the string "QQQQ" and this tool doesn't take that into account. E.g., I type this into my javascript console: /A*/.test('QQQQ'); > true Showing that yes, /A / does match 'QQQQ'

Actually this is wrong, when you use A* in vim for example you're not looking exactly for A* but for substring containing an A* since this also matches "" programs like vim will match anything.

Just because these tools use regex this way doesn't mean that's how regex really works.

Re: Regex Crossword

#113

Post by mgraczyk »

toastedzergling wrote: post #102
mgraczyk wrote: post #64

Earlier quoted context omitted.

That isn't how the Kleene star works. A* is "the set of all strings over the alphabet {A}, including the empty string ε." "QQQQ" is not a string over the alphabet {A} because it contains the symbol 'Q', which is not in {A}.

I have no idea what you're talking about. My point is more pragmatic the regex /A / will match the string "QQQQ" and this tool doesn't take that into account. E.g., I type this into my javascript console: /A*/.test('QQQQ'); > true Showing that yes, /A / does match 'QQQQ'

No, it doesn't. It matches the empty string at the beginning of 'QQQQ', not the Qs themselves:

    /A*/.exec('QQQQ')
    [""]
When computer scientists discuss what a regular express does and does not "match", they are saying that strings which are "matched" by a regex are those strings which are members of the regular language defined by the regex. QQQQ is not a string in the language defined by /A* /, so /A* / does not match QQQQ.

If we look at things your way, we would have to say that the regex /A/ matches "AQQQQ". It does not. It matches "A".

Re: Regex Crossword

#114

Post by wodenokoto »

toastedzergling wrote: post #103
bmm6o wrote: post #87

Earlier quoted context omitted.

* is not a wildcard, it indicates that the preceding token occurs zero or more times.

Yes, that's exactly my point. By occuring zero times, it means the preceeding token is irrelevant, and will match any arbitrary string.

So you are saying that // will match any arbitrary string?

Re: Regex Crossword

#115

Post by baby »

rev_bird wrote: post #76
zatkin wrote: post #61

Earlier quoted context omitted.

Anything 0 or more times backreferenced onto the end of the string "DO", is my guess. So, for example: DO DONUT DOG

Wouldn't the characters have to come first, in order to be referenced in the first place? I.e. "DOG" would read "GDOG," no?

yes, parent is wrong.
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