Split string by commas ignoring any punctuation marks (including ',') in quotation marks

Question

How can I split string (from a textbox) by commas excluding those in double quotation marks (without getting rid of the quotation marks), along with other possible punctuation marks (e.g. ' . ' ' ; ' ' - ')?

E.g. If someone entered the following into the textbox:

apple, orange, "baboons, cows", rainbow, "unicorns, gummy bears"

How can I split the above string into the following (say, into a List)?

apple

orange

"baboons, cows"

rainbow

"Unicorns, gummy bears..."

Thank you for your help!

Answer 1

You could try the below regex which uses positive lookahead,

string value = @"apple, orange, ""baboons, cows"", rainbow, ""unicorns, gummy bears""";
string[] lines = Regex.Split(value, @", (?=(?:""[^""]*?(?: [^""]*)*))|, (?=[^"",]+(?:,|$))");

foreach (string line in lines) {
Console.WriteLine(line);
}

Output:

apple
orange
"baboons, cows"
rainbow
"unicorns, gummy bears"

IDEONE

Answer 2

Try this:

Regex str = new Regex("(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)", RegexOptions.Compiled);

foreach (Match m in str.Matches(input))
{
    Console.WriteLine(m.Value.TrimStart(','));
}

You may also try to look at FileHelpers

Answer 3

Much like a CSV parser, instead of Regex, you can loop through each character, like so:

public List<string> ItemStringToList(string inputString)
{  
    var itemList   = new List<string>();
    var currentIem = "";
    var quotesOpen = false;

    for (int i = 0; i < inputString.Length; i++)
    {
        if (inputString[i] == '"')
        {
            quotesOpen = !quotesOpen;
            continue;
        }

        if (inputString[i] == ',' && !quotesOpen)
        {
            itemList.Add(currentIem);
            currentIem = "";
            continue;
        }

        if (currentIem == "" && inputString[i] == ' ') continue;
        currentIem += inputString[i];
    }

    if (currentIem != "") itemList.Add(currentIem);

    return itemList;
}

Example test usage:

var test1 = ItemStringToList("one, two, three");
var test2 = ItemStringToList("one, \"two\", three");
var test3 = ItemStringToList("one, \"two, three\"");
var test4 = ItemStringToList("one, \"two, three\", four, \"five six\", seven");
var test5 = ItemStringToList("one, \"two, three\", four, \"five six\", seven");
var test6 = ItemStringToList("one, \"two, three\", four, \"five six, seven\"");
var test7 = ItemStringToList("\"one, two, three\", four, \"five six, seven\"");

You could change it to use StringBuilder if you want faster character joining.

Answer 4

Try with this it will work u c an split array string in many waysif you want to split by white space just put a space in (' ') .

  namespace LINQExperiment1
  {
  class Program
  {
  static void Main(string[] args)
  {
   string[] sentence = new string[] { "apple", "orange", "baboons  cows", " rainbow", "unicorns  gummy bears" };

  Console.WriteLine("option 1:"); Console.WriteLine("————-");
  // option 1: Select returns three string[]’s with
  // three strings in each.
  IEnumerable<string[]> words1 =
  sentence.Select(w => w.Split(' '));
  // to get each word, we have to use two foreach loops
  foreach (string[] segment in words1)
  foreach (string word in segment)
  Console.WriteLine(word);
  Console.WriteLine();
  Console.WriteLine("option 2:"); Console.WriteLine("————-");
  // option 2: SelectMany returns nine strings
  // (sub-iterates the Select result)
  IEnumerable<string> words2 =
  sentence.SelectMany(segment => segment.Split(','));
  // with SelectMany we have every string individually
  foreach (var word in words2)
  Console.WriteLine(word);
  // option 3: identical to Opt 2 above written using
  // the Query Expression syntax (multiple froms)
  IEnumerable<string> words3 =from segment in sentence
  from word in segment.Split(' ')
  select word;
   }
  }
 }

Answer 5

This was trickier than I thought, a good practical problem I think.

Below is the solution I came up with for this. One thing I don't like about my solution is having to add double quotations back and the other one being names of the variables :p:

internal class Program
{
    private static void Main(string[] args)
    {

        string searchString =
            @"apple, orange, ""baboons, cows. dogs- hounds"", rainbow, ""unicorns, gummy bears"", abc, defghj";

        char delimeter = ',';
        char excludeSplittingWithin = '"';

        string[] splittedByExcludeSplittingWithin = searchString.Split(excludeSplittingWithin);

        List<string> splittedSearchString = new List<string>();

        for (int i = 0; i < splittedByExcludeSplittingWithin.Length; i++)
        {
            if (i == 0 || splittedByExcludeSplittingWithin[i].StartsWith(delimeter.ToString()))
            {
                string[] splitttedByDelimeter = splittedByExcludeSplittingWithin[i].Split(delimeter);
                for (int j = 0; j < splitttedByDelimeter.Length; j++)
                {
                    splittedSearchString.Add(splitttedByDelimeter[j].Trim());
                }
            }
            else
            {
                splittedSearchString.Add(excludeSplittingWithin + splittedByExcludeSplittingWithin[i] +
                                         excludeSplittingWithin);
            }
        }

        foreach (string s in splittedSearchString)
        {
            if (s.Trim() != string.Empty)
            {
                Console.WriteLine(s);
            }
        }
        Console.ReadKey();
    }
}

Answer 6

Another Regex solution:

private static IEnumerable<string> Parse(string input)
{
  // if used frequently, should be instantiated with Compiled option
  Regex regex = new Regex(@"(?<=^|,\s)(\""(?:[^\""]|\""\"")*\""|[^,\s]*)");

  return regex.Matches(inputData).Where(m => m.Success);
}