System.Data.SqlClient.SqlDataReader.SqlDataReader.GetChars C# (CSharp) Method

		long GetChars (int i, long dataIndex, char[] buffer, int bufferIndex, int length)
		{
			if ((command.CommandBehavior & CommandBehavior.SequentialAccess) != 0) {
				ValidateState ();
				EnsureDataAvailable ();

				if (i < 0 || i >= command.Tds.Columns.Count)
					throw new IndexOutOfRangeException ();

				Encoding encoding = null;
				byte mul = 1;
				TdsColumnType colType = (TdsColumnType) command.Tds.Columns[i]["ColumnType"];
				switch (colType) {
					case TdsColumnType.Text :
					case TdsColumnType.VarChar:
					case TdsColumnType.Char:
					case TdsColumnType.BigVarChar:
						encoding = Encoding.ASCII;
						break;
					case TdsColumnType.NText :
					case TdsColumnType.NVarChar:
					case TdsColumnType.NChar:
						encoding = Encoding.Unicode;
						mul = 2;
						break;
					default :
						return -1;
				}

				long count = 0;
				if (buffer == null) {
					count = GetBytes (i,0,(byte[]) null,0,0);
					return (count/mul);
				}

				length *= mul;
				byte[] arr = new byte [length];
				count = GetBytes (i, dataIndex, arr, 0, length);
				if (count == -1)
					throw new InvalidCastException ("Specified cast is not valid");

				Char[] val = encoding.GetChars (arr, 0, (int)count);
				val.CopyTo (buffer, bufferIndex);
				return val.Length;
			}

			char [] valueBuffer;
			object value = GetValue (i);
			
			if (value is char[])
				valueBuffer = (char[])value;
			else if (value is string)
				valueBuffer = ((string)value).ToCharArray();
			else {
				if (value is DBNull) throw new SqlNullValueException ();
				throw new InvalidCastException ("Type is " + value.GetType ().ToString ());
			}
			
			if ( buffer == null ) {
				// Return length of data
				return valueBuffer.Length;
			}
			else {
				// Copy data into buffer
				Array.Copy (valueBuffer, (int) dataIndex, buffer, bufferIndex, length);
				return valueBuffer.Length - dataIndex;
			}
		}