String list in SqlCommand through Parameters in C#

SELECT blahblahblah WHERE blahblahblah IN @LISTOFWORDS

DataTable dt = new DataTable();
dt.Columns.Add("word", typeof(string));
foreach (String word in listOfWords)
{
    dt.Rows.Add(word);
}
comm.Parameters.Add("LISTOFWORDS", System.Data.SqlDbType.Structured).Value = dt;

SELECT * FROM [Table] WHERE ID IN (1,2,3)

SELECT * FROM [Table] WHERE ID IN ( SELECT TableID FROM [OtherTable] WHERE OtherTableID= @OtherTableID )

StringBuilder sb = new StringBuilder();
for (int i=0; i< listOfWords.Count; i++)
{
    sb.AppendFormat("p{0},",i);
    comm.Parameters.AddWithValue("p"+i.ToString(), listOfWords[i]);
}

comm.CommandText = string.Format(""SELECT blahblahblah WHERE blahblahblah IN ({0})",
sb.ToString().TrimEnd(','));

SELECT blah WHERE blah IN (p0,p1,p2,p3...)...p0='aaa',p1='bbb'

ALTER FUNCTION [dbo].[Split]
(
    @RowData nvarchar(max),
    @SplitOn nvarchar(5) = ','
)
RETURNS @RtnValue table
(
    Id int identity(1,1),
    Data nvarchar(100)
)
AS
BEGIN
    Declare @Cnt int
    Set @Cnt = 1

    While (Charindex(@SplitOn,@RowData)>0)
    Begin
        Insert Into @RtnValue (data)
        Select
            Data = ltrim(rtrim(Substring(@RowData,1,Charindex(@SplitOn,@RowData)-1)))

        Set @RowData = Substring(@RowData,Charindex(@SplitOn,@RowData)+1,len(@RowData))
        Set @Cnt = @Cnt + 1
    End

    Insert Into @RtnValue (data)
    Select Data = ltrim(rtrim(@RowData))

    Return
END

Select Id, Data from dbo.Split('123,234,345,456',',')

CREATE PROCEDURE [dbo].[findDuplicates]
    @ids nvarchar(max)
as
begin
    select ID
      from SomeTable with (nolock)
     where ID in (select Data from dbo.Split(@ids,','))
end

public void SomeFunction(List<int> ids)
{
    var idsAsDelimitedString = string.Join(",", ids.Select(id => id.ToString()).ToArray());

    // ... or however you make your connection
    var con = GetConnection();

    try
    {
        con.Open();

        var cmd = new SqlCommand("findDuplicates", con);

        cmd.Parameters.Add(new SqlParameter("@ids", idsAsDelimitedString));

        var reader = cmd.ExecuteReader();

        // .... do something here.

    }
    catch (Exception)
    {
        // catch an exception?
    }
    finally
    {
        con.Close();
    }
}