How can I Split(',') a string while ignore commas in between quotes?

Question

I am using the .Split(',') method on a string that I know has values delimited by commas and I want those values to be separated and put into a string[] object. This works great for strings like this:

78,969.82,GW440,.

But the values start to look different when that second value goes over 1000, like the one found in this example:

79,"1,013.42",GW450,....

These values are coming from a spreadsheet control where I use the controls built in ExportToCsv(...) method and that explains why a formatted version of the actual numerical value.

Question

Is there a way I can get the .Split(',') method to ignore commas inside of quotes? I don't actually want the value "1,013.42" to be split up as "1 and 013.42".

Any ideas? Thanks!

Update

I really would like to do this without incorporating a 3rd party tool as my use case really doesn't involve many other cases besides this one and even though it is part of my work's solution, having a tool like that incorporated doesn't really benefit anyone at the moment. I was hoping there was something quick to solve this particular use case that I was missing, but now that it is the weekend, I'll see if I can't give one more update to this question on Monday with the solution I eventually come up with. Thank you everyone for you assistance so far, I'll will assess each answer further on Monday.

Answer 1

You should probably read this article: Regular Expression for Comma Based Splitting Ignoring Commas inside Quotes Although it is for Java, but the regular expression is the same.

Answer 2

This is a fairly straight forward CSV Reader implementation we use in a few projects here. Easy to use and handles those cases you are talking about.

First the CSV Class

public static class Csv
{
    public static string Escape(string s)
    {
        if (s.Contains(QUOTE))
            s = s.Replace(QUOTE, ESCAPED_QUOTE);

        if (s.IndexOfAny(CHARACTERS_THAT_MUST_BE_QUOTED) > -1)
            s = QUOTE + s + QUOTE;

        return s;
    }

    public static string Unescape(string s)
    {
        if (s.StartsWith(QUOTE) && s.EndsWith(QUOTE))
        {
            s = s.Substring(1, s.Length - 2);

            if (s.Contains(ESCAPED_QUOTE))
                s = s.Replace(ESCAPED_QUOTE, QUOTE);
        }

        return s;
    }


    private const string QUOTE = "\"";
    private const string ESCAPED_QUOTE = "\"\"";
    private static char[] CHARACTERS_THAT_MUST_BE_QUOTED = { ',', '"', '\n' };

}

Then a pretty nice Reader implementation - If you need it. You should be able to do what you need with just the CSV class above.

public sealed class CsvReader : System.IDisposable
{
    public CsvReader(string fileName)
        : this(new FileStream(fileName, FileMode.Open, FileAccess.Read))
    {
    }

    public CsvReader(Stream stream)
    {
        __reader = new StreamReader(stream);
    }

    public System.Collections.IEnumerable RowEnumerator
    {
        get
        {
            if (null == __reader)
                throw new System.ApplicationException("I can't start reading without CSV input.");

            __rowno = 0;
            string sLine;
            string sNextLine;

            while (null != (sLine = __reader.ReadLine()))
            {
                while (rexRunOnLine.IsMatch(sLine) && null != (sNextLine = __reader.ReadLine()))
                    sLine += "\n" + sNextLine;

                __rowno++;
                string[] values = rexCsvSplitter.Split(sLine);

                for (int i = 0; i < values.Length; i++)
                    values[i] = Csv.Unescape(values[i]);

                yield return values;
            }

            __reader.Close();
        }

    }

    public long RowIndex { get { return __rowno; } }

    public void Dispose()
    {
        if (null != __reader) __reader.Dispose();
    }

    //============================================


    private long __rowno = 0;
    private TextReader __reader;
    private static Regex rexCsvSplitter = new Regex(@",(?=(?:[^""]*""[^""]*"")*(?![^""]*""))");
    private static Regex rexRunOnLine = new Regex(@"^[^""]*(?:""[^""]*""[^""]*)*""[^""]*$");

}

Then you can use it like this.

var reader = new CsvReader(new FileStream(file, FileMode.Open));

Note: This would open an existing CSV file, but can be modified fairly easily to take a string[] like you need.