How to split string in C# using comma when string also contain comma-CodePudding

I have following string:

1, 20045, abc, "new york, some2", new york, your name

How do I split this string using comma when it also contains comma in one of the values?

CodePudding user response：

As the comments by @jmcilhinney mention, you should ideally be using a CSV parser here. If you want to go the splitting approach, I would suggest a regex find all on the following pattern:

".*?"|[^\s,] (?: [^\s,] )*

This pattern says to match:

".*?" first try to consume a doubly quoted term, possibly containing commas
| OR
[^\s,] match a term not including comma
(?: [^\s,] )* possibly followed by space and another term, 0 or more times

This regex trick eagerly matches doubly quoted terms, and only that failing will use comma as a separator.

Sample script:

string text = "1, 20045, abc, \"new york, some2\", new york, your name";
string search = @""".*?""|[^\s,] (?: [^\s,] )*";
MatchCollection matches = Regex.Matches(text, search);
foreach (Match match in matches)
{
    GroupCollection groups = match.Groups;
    Console.WriteLine(groups[0].Value);
}

This prints:

1
20045
abc
"new york, some2"
new york
your name

CodePudding user response：

It is likely best to pick some library that can handle CSV files.

Otherwise, this could work in cases like yours:

public static string[] Split(string str)
{
    var indices = new List<int>();
    var insideQuote = false;
    for (var i = 0; i < str.Length;   i)
    {
        switch (str[i])
        {
            case '"':
                insideQuote ^= true;
                break;
            case ',':
                if (!insideQuote) { indices.Add(i); }
                break;
        }
    }
    if (indices.Count == 0)
    {
        return new[] { str, };
    }

    var arr = new string[indices.Count   1];
    arr[0] = str.Substring(0, indices[0]);
    for (var i = 1; i < arr.Length - 1;   i)
    {
        arr[i] = str.Substring(indices[i - 1]   1, indices[i] - indices[i - 1] - 1);
    }
    arr[arr.Length - 1] = str.Substring(indices[arr.Length - 2]   1);

    return arr;
}