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"Field1","Field2","item1,item2,item3","Hello,""John"""

The one thing I understand is it is splitting the string on , but anything after that I am not sure.

If anyone can explain this Regex please.

If you can dissect it to the simplest possible level, I would appreciate it.

, -> match literal comma
(?=...) -> positive lookahead
[^"]*" -> match anything before a " followed by a literal "
[^"]*"[^"]*" -> match a pair of above 
(?:[^"]*"[^"]*")* -> Match 0 or more of pairs (0, 2, 4, 6 sets)
[^"]*$ -> Followed by any non-quote till end of string
Example Input:
"Field1,Field2","Field3","item1,item2,item3"
First it will match , before "Field3" because lookahead: (?=(?:[^"]*"[^"]*")*[^"]*$) is making sure there are 4 double quotes after this comma.
Second it will match , after "Field3" because lookahead: (?=(?:[^"]*"[^"]*")*[^"]*$) is making sure there are 2 double quotes after this comma.
It is not matching comma between Field1 and Field2 because # of quotes after that are odd in numbers and hence lookahead (?=(?:[^"]*"[^"]*")*[^"]*$) will fail.
                I understand that part but need to understand it part by part so I can create something similar myself.
– gbs
                Nov 7, 2014 at 21:09
                Thanks got little more understanding but would it be possible to explain a bit more using the example string I have above.
– gbs
                Nov 7, 2014 at 21:26
                ok see this demo link with above regex and a simplified example. I will add more explanation
– anubhava
                Nov 7, 2014 at 21:32
                Now your initial explanation steps makes more sense to me. The demo link was helpful. Thanks.
– gbs
                Nov 7, 2014 at 22:00
                Thanks...I understand that part but need to understand it part by part so I can create something similar myself.
– gbs
                Nov 7, 2014 at 21:09
                @gbs if a , is in between " and " it will have odd number of " ahead of it.If it is outside it will have even number of " ahead of it.hope that helps
– vks
                Nov 7, 2014 at 21:14
        
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