System.IO.Compression.Zip64ExtraField.UpdateSize C# (CSharp) Method

        private void UpdateSize()
        {
            _size = 0;
            if (_uncompressedSize != null) _size += 8;
            if (_compressedSize != null) _size += 8;
            if (_localHeaderOffset != null) _size += 8;
            if (_startDiskNumber != null) _size += 4;
        }