Question

I am looking to split such string by comma :

 field1:"value1", field2:"value2", field3:"value3,value4"

into a string[] that would look like:

0     field1:"value1"
1     field2:"value2"
2     field3:"value3,value4"

I am trying to do that with Regex.Split but can’t seem to work out the regular expression.

Answer 1

It’ll be much easier to do this with Matches than with Split, for example

string[] asYouWanted = Regex.Matches(input, @"[A-Za-z0-9]+:"".*?""")
    .Cast<Match>()
    .Select(m => m.Value)
    .ToArray();

although if there is any chance of your values (or fields!) containing escaped quotes (or anything similarly tricky), then you might be better off with a proper CSV parser.

---

If you do have escaped quotes in your values, I think the following regex the work – give it a test:

@"field3:""value3\\"",value4""", @"[A-Za-z0-9]+:"".*?(?<=(?<!\\)(\\\\)*)"""

The added (?<=(?<!\\)(\\\\)*) is supposed to make sure that the " it stops matching on is preceeded by only an even number of slashes, as an odd number of slashes means it is escaped.