Convert a BitArray to byte[] in C#

Here’s an extension method that packs a C# BitArray to a byte array:

public
static byte[] ToByteArray(this BitArray bits) {
  int numBytes = bits.Count / 8;
  if (bits.Count % 8 != 0) numBytes++;

  byte[] bytes = new byte[numBytes];
  int byteIndex = 0, bitIndex = 0;

  for (int i = 0; i < bits.Count; i++) {
    if (bits[i]) bytes[byteIndex] |= (byte)(1 << (7 - bitIndex));

    bitIndex++;
    if (bitIndex == 8) {
      bitIndex = 0;
      byteIndex++;
    }
  }

  return bytes;
}

Special thanks to the good people at StackOverflow! Enjoy!