How to convert long array into byte array?

Question

Data comes from outside of the program as long array has to be converted into byte array. how to do that efficiently? As well, is there are way to select type of convertion as Little Endian or Big Endian.

Do you mean that every long in the source array should become 8 bytes in the destination array? (And that the conversion process should be capable of handling different endian-ness?) — LukeH
– LukeH, Commented May 22, 2012 at 15:10
Please give an unambiguous example of a given input and what its output would be. — Gabe
– Gabe, Commented May 22, 2012 at 15:13

Guffa · Accepted Answer · 2012-05-22 15:20:12Z

5

You can do like this to convert a long array to a byte array:

bool isLittleEndian = true;
byte[] data = new byte[longData.Length * 8];
int offset = 0;
foreach (long value in longData) {
  byte[] buffer = BitConverter.GetBytes(value);
  if (BitConverter.IsLittleEndian != isLittleEndian) {
    Array.Reverse(buffer);
  }
  buffer.CopyTo(data, offset);
  offset += 8;
}

This is usually efficient enough. If you need it to be faster, you should use pointers in an unsafe code block.

answered May 22, 2012 at 15:20

Guffa

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3 Comments

baraban Over a year ago

do you think is possible to use unmanaged memcpy in case if input array is IsLittleEndian? Is there are any sample on how to do that?

Guffa Over a year ago

@baraban: If the source and destination endianess is the same, you can use unmanaged block copy.

Guffa Over a year ago

@baraban: Yes, that seems to be usable.

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