issue with byte array, I cant Shift left byte

Question

I want to convert a string containing a binary number into an array of bytes. For that, I have this function:

private byte[] ToByteArray(string StringToConvert)
{
   byte[] ByteArray = new byte[StringToConvert.Length/8];
   byte temp;
   for (int i = 0; i < StringToConvert.Length; i=i+8)
   {
      for (int j = i; j < 8; j++)
      {
         temp = Convert.ToByte(StringToConvert[j]);
         ByteArray[i]=ByteArray[i] << temp;
      }
   }

   return ByteArray;
}

I get an error that I can not convert byte to int(?) at

ByteArray[i]=ByteArray[i]<< temp;

What am I doing wrong?

Answer 1

This will convert a string containing a binary number like "001011101101011010101011" into a byte array { 46, 214, 171 }.

private Byte[] ToByteArray(String stringToConvert)
{
   Contract.Requires(stringToConvert != null);
   Contract.Requires(stringToConvert.Length % 8 == 0);

   var result = new Byte[stringToConvert.Length / 8];

   for (var index = 0; index < stringToConvert.Length / 8; index++)
   {
      result[index] = Convert.ToByte(stringToConvert.Substring(index * 8, 8), 2);
   }

   return result;
}

Answer 2

Use

ByteArray[i] = (byte)(ByteArray[i] << temp);

As mentioned on MSDN (Shift Operators), the following is the predefined shift operators

int operator <<(int x, int count);
uint operator <<(uint x, int count);
long operator <<(long x, int count);
ulong operator <<(ulong x, int count);

and the byte values (ByteArray[i]) matches the first operator specification which is then invoked and returns an int value. So, to store the int value in byte, you have to typecast it to byte. As int to byte is not implicit (data loss may occur), so you have to explicitly do the cast, as shown in the line above.

Answer 3

I'm going to read between the lines and guess that StringToConvert is a string containing multiples of 8 '0's or '1's, and that what you are trying to do is convert it to an array of bytes.

private byte[] ToByteArray(string StringToConvert)
{
    byte[] ByteArray = new byte[StringToConvert.Length/8];
    for (int i = 0; i < StringToConvert.Length/8; i++)
    {
        for (int j = 0; j < 8; j++)
        {
            char bitStr = StringToConvert[i*8+j];
            ByteArray[i] = (byte)((ByteArray[i] << 1) | (bit=='1' ? 1 : 0));
        }
    }

    return ByteArray;
}