C＃无法隐式将类型'Char []'转换为'Char？'

Question

I searched and searched, but couldn't find anything remotely similar. According to everything I've come to know, it should work.

  string strTest, strSubTest, strDesc;
        using (GenericParser parser = new GenericParser())
        {
            parser.SetDataSource(@"D:\work.csv");

            parser.ColumnDelimiter = @",".ToCharArray();
            parser.FirstRowHasHeader = true;
            parser.MaxBufferSize = 4096;
            parser.MaxRows = 200;

            while (parser.Read())
            {
                strTest = parser["Test"];
                strSubTest = parser["Subtest"];
                strDesc = parser["Description"];
                Console.WriteLine(strTest);

The code that states @",".ToCharArray(); states the error in the title. I've never seen an implicit conversion like that before 'Char?'. Any idea what I did wrong?

If you need some background, I used the GenericParser found here: http://www.codeproject.com/Articles/11698/A-Portable-and-Efficient-Generic-Parser-for-Flat-F

Answer 1

（请注意单引号）

parser.ColumnDelimiter = ',';

Answer 2

the question mark is a modifier to value types like char, int, and double to make them nullable. So where char x = null; is a syntax error, char? x = null; char? x = null; works. char? actually a shorthand syntax for Nullable<char> . Nullable<T> can't be used with reference types, as they are already nullable. Nullable<T> objects have two properties, bool HasValue , which should be obvious, and T Value , which returns the encapsulated value if HasValue is true, or throws an exception if it is false.

So, you can't set Delimeter to a character array, because it is expecting either a character or null.