正则表达式用c＃中的逗号和双引号拆分字符串

Question

I have tried a regular expression to split a string with comma and space. Expression matches all the cases except only one. The code I have tried is:

        List<string> strNewSplit = new List<string>();
        Regex csvSplit = new Regex("(?:^|,)(\"(?:[^\"]+|\"\")*\"|[^,]*)", RegexOptions.Compiled);
        foreach (Match match in csvSplit.Matches(input))
        {
            strNewSplit.Add(match.Value.TrimStart(','));
        }
        return strNewSplit;

CASE1: "MYSQL,ORACLE","C#,ASP.NET"

EXpectedOutput:

"MYSQL,ORACLE"

"C#,ASP.NET"

RESULT : PASS

CASE2: "MYSQL,ORACLE", "C#,ASP.NET"

ExpectedOutput:

"MYSQL,ORACLE"

"C#,ASP.NET"

Actual OutPut:

"MYSQL,ORACLE"

"C#

ASP.NET"

RESULT: FAIL.

If I provide a space after a comma in between two DoubleQuotes then I didn't get appropriate output. Am I missing anything? Please provide a better solution.

Answer 1

I normally write down the EBNF of my Input to parse.

In your case I would say:

List = ListItem {Space* , Space* ListItem}*;

ListItem = """ Identifier """; // Identifier is everything whitout "

Space = [\\t ]+;

Which means a List consists of a ListItem that is folled by zero or mutliple (*) ListItems that are separated with spaces a comma and again spaces.

That lead me to the following (you are searching for ListItems):

static void Main(string[] args)
{
    matchRegex("\"MYSQL,ORACLE\",\"C#,ASP.NET\"").ForEach(Console.WriteLine);
    matchRegex("\"MYSQL,ORACLE\", \"C#,ASP.NET\"").ForEach(Console.WriteLine);
}
static List<string> matchRegex(string input)
{
    List<string> strNewSplit = new List<string>();
    Regex csvSplit = new Regex(
        "(\"(?:[^\"]*)\")"
        , RegexOptions.Compiled);
    foreach (Match match in csvSplit.Matches(input))
    {
       strNewSplit.Add(match.Value.TrimStart(','))
    }
    return strNewSplit;
}

Which returns what you wanted. Hope I understood you correctly.