Optimize Comma Separated Values Regular Expression

Question

I am creating a string array of comma separated values. I need to split the line on commas but not commas that are inside quotes as that could be part of the data.

For example:
\"421 15th Ave.\",\"Beaver Falls, PA\",\"S1\",

I wouldn't want it to split between the city and state for a new field.

Here is the code currently:

string[] fields = Regex.Split(lines[i], @",(?=(?:[^""]*""[^""]*"")*(?![^""]*""))");

It takes a long time to execute. Is there a better option I could be using?

Thanks for any help on this.

Are you required to use regex? CSV is often best tackled using plain old string methods. — Gusdor
– Gusdor, Commented Dec 10, 2013 at 16:01
I am not required to use regex that is just what is currently in place. Looking for a better option. Which string method(s) would you suggest to solve this? — Baxter
– Baxter, Commented Dec 10, 2013 at 16:08
Use some sort of csv reader. Assuming you're using a decent one, this will already be handled and the code should be optimized. — Steve P.
– Steve P., Commented Dec 10, 2013 at 16:09
You might gain even more performance if you parallelize the spliting file lines between processors, using Parallel.ForEach & Parititioner.Create. This way you can process LINES0-1000 on a processor1, and LINES1001-2000 on a processor2, yielding you 2x improvement. — Erti-Chris Eelmaa
– Erti-Chris Eelmaa, Commented Dec 10, 2013 at 16:24

Community · Accepted Answer · 2017-05-23 11:49:44Z

1

Have you considered using a CSV-Reader? This CSV-Reader should already handle the case of commas inside double quotes: OpenCsv

See Ravi Thapliyal's answer in this thread about how to use it: link

For C# I can recommend this CsvHelper: https://github.com/JoshClose/CsvHelper

We use it in our project and it's very handy

edited May 23, 2017 at 11:49

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answered Dec 10, 2013 at 16:08

xeraphim

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3 Comments

Baxter Over a year ago

Is there a C# equivalent to this?

xeraphim Over a year ago

Hey Baxter I updated my answer just before you commented :-) See the CsvHelper link in my answer above

xeraphim Over a year ago

Hey Baxter if this answer helped I would appreciate, if you could mark it as accepted answer :-) thanks

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