System.Data.Common.DataRecordInternal.GetChars C# (CSharp) Method

        public override long GetChars(int i, long dataIndex, char[] buffer, int bufferIndex, int length)
        {
            // if the object doesn't contain a char[] then the user will get an exception
            string s = (string)_values[i];

            char[] data = s.ToCharArray();

            int cchars = data.Length;

            // since arrays can't handle 64 bit values and this interface doesn't
            // allow chunked access to data, a dataIndex outside the rang of Int32
            // is invalid
            if (dataIndex > int.MaxValue)
            {
                throw ADP.InvalidSourceBufferIndex(cchars, dataIndex, nameof(dataIndex));
            }

            int ndataIndex = (int)dataIndex;


            // if no buffer is passed in, return the number of characters we have
            if (null == buffer)
            {
                return cchars;
            }

            try
            {
                if (ndataIndex < cchars)
                {
                    // help the user out in the case where there's less data than requested
                    if ((ndataIndex + length) > cchars)
                    {
                        cchars = cchars - ndataIndex;
                    }
                    else
                    {
                        cchars = length;
                    }
                }

                Array.Copy(data, ndataIndex, buffer, bufferIndex, cchars);
            }
            catch (Exception e) when (ADP.IsCatchableExceptionType(e))
            {
                cchars = data.Length;

                if (length < 0)
                {
                    throw ADP.InvalidDataLength(length);
                }

                // if bad buffer index, throw
                if (bufferIndex < 0 || bufferIndex >= buffer.Length)
                {
                    throw ADP.InvalidDestinationBufferIndex(buffer.Length, bufferIndex, nameof(bufferIndex));
                }

                // if bad data index, throw
                if (ndataIndex < 0 || ndataIndex >= cchars)
                {
                    throw ADP.InvalidSourceBufferIndex(cchars, dataIndex, nameof(dataIndex));
                }

                // if there is not enough room in the buffer for data
                if (cchars + bufferIndex > buffer.Length)
                {
                    throw ADP.InvalidBufferSizeOrIndex(cchars, bufferIndex);
                }
            }

            return cchars;
        }