split a comma-separated string with both quoted and unquoted strings

user_455937 0
Viewed 97909

I have the following comma-separated string that I need to split. The problem is that some of the content is within quotes and contains commas that shouldn't be used in the split.

String:

111,222,"33,44,55",666,"77,88","99"

I want the output:

111  
222  
33,44,55  
666  
77,88  
99

I have tried this: 

(?:,?)((?<=")[^"]+(?=")|[^",]+)

But it reads the comma between "77,88","99" as a hit and I get the following output: 

111  
222  
33,44,55  
666  
77,88  
,  
99
regex c#
16 Answers

Try this

private string[] GetCommaSeperatedWords(string sep, string line)
    {
        List<string> list = new List<string>();
        StringBuilder word = new StringBuilder();
        int doubleQuoteCount = 0;
        for (int i = 0; i < line.Length; i++)
        {
            string chr = line[i].ToString();
            if (chr == "\"")
            {
                if (doubleQuoteCount == 0)
                    doubleQuoteCount++;
                else
                    doubleQuoteCount--;

                continue;
            }
            if (chr == sep && doubleQuoteCount == 0)
            {
                list.Add(word.ToString());
                word = new StringBuilder();
                continue;
            }
            word.Append(chr);
        }

        list.Add(word.ToString());

        return list.ToArray();
    }
user_24174450

This is Chad's answer rewritten with state based logic. His answered failed for me when it came across """BRAD""" as a field. That should return "BRAD" but it just ate up all the remaining fields. When I tried to debug it I just ended up rewriting it as state based logic:

enum SplitState { s_begin, s_infield, s_inquotefield, s_foundquoteinfield };
public static IEnumerable<string> SplitRow(string row, char delimiter = ',')
{
    var currentString = new StringBuilder();
    SplitState state = SplitState.s_begin;
    row = string.Format("{0}{1}", row, delimiter); //We add new cells at the delimiter, so append one for the parser.
    foreach (var character in row.Select((val, index) => new { val, index }))
    {
        //Console.WriteLine("character = " + character.val + " state = " + state);
        switch (state)
        {
            case SplitState.s_begin:
                if (character.val == delimiter)
                {
                    /* empty field */
                    yield return currentString.ToString();
                    currentString.Clear();
                } else if (character.val == '"')
                {
                    state = SplitState.s_inquotefield;
                } else
                {
                    currentString.Append(character.val);
                    state = SplitState.s_infield;
                }
                break;
            case SplitState.s_infield:
                if (character.val == delimiter)
                {
                    /* field with data */
                    yield return currentString.ToString();
                    state = SplitState.s_begin;
                    currentString.Clear();
                } else
                {
                    currentString.Append(character.val);
                }
                break;
            case SplitState.s_inquotefield:
                if (character.val == '"')
                {
                    // could be end of field, or escaped quote.
                    state = SplitState.s_foundquoteinfield;
                } else
                {
                    currentString.Append(character.val);
                }
                break;
            case SplitState.s_foundquoteinfield:
                if (character.val == '"')
                {
                    // found escaped quote.
                    currentString.Append(character.val);
                    state = SplitState.s_inquotefield;
                }
                else if (character.val == delimiter)
                {
                    // must have been last quote so we must find delimiter
                    yield return currentString.ToString();
                    state = SplitState.s_begin;
                    currentString.Clear();
                }
                else
                {
                    throw new Exception("Quoted field not terminated.");
                }
                break;
            default:
                throw new Exception("unknown state:" + state);
        }
    }
    //Console.WriteLine("currentstring = " + currentString.ToString());
}

This is a lot more lines of code than the other solutions, but it is easy to modify to add edge cases.

user_1920440
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