Question

I have an array of 128 booleans that represent bits. How can I convert these 128 bit representations into 16 bytes?

Example:

I have an array that looks like this:

0110001100110000100010111011001011010011010001010001101101001100 1000010000000000001000111111111101000011111001111011111011111001 

(Converted to 1s and 0s to be more concise)

I need to convert those bits to the following byte array:

99 48 139 178 211 69 27 76 132 0 35 255 67 231 190 249 

EDIT: This doesn’t seem to work:

public byte[] ToByteArray() {     int numBytes = 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 << bitIndex);          bitIndex++;         if (bitIndex == 8) {             bitIndex = 0;             byteIndex++;         }     }      return bytes; } 

It outputs:

198 12 209 77 203 162 216 50 33 0 196 255 194 231 125 159 

Answer 1

The code is treating the first bit as the low bit of the word, so you end up with each word reversed. As a quick-and-dirty fix, try this:

bytes[byteIndex] |= (byte)(1 << (7-bitIndex)); 

That puts the first bit in the array at the highest position in the first byte, etc.