Removing trailing nulls from byte array in C#

Question

Ok, I am reading in dat files into a byte array. For some reason, the people who generate these files put about a half meg's worth of useless null bytes at the end of the file. Anybody know a quick way to trim these off the end?

First thought was to start at the end of the array and iterate backwards until I found something other than a null, then copy everything up to that point, but I wonder if there isn't a better way.

To answer some questions: Are you sure the 0 bytes are definitely in the file, rather than there being a bug in the file reading code? Yes, I am certain of that.

Can you definitely trim all trailing 0s? Yes.

Can there be any 0s in the rest of the file? Yes, there can be 0's other places, so, no, I can't start at the beginning and stop at the first 0.

Answer 1

I agree with Jon. The critical bit is that you must "touch" every byte from the last one until the first non-zero byte. Something like this:

byte[] foo;
// populate foo
int i = foo.Length - 1;
while(foo[i] == 0)
    --i;
// now foo[i] is the last non-zero byte
byte[] bar = new byte[i+1];
Array.Copy(foo, bar, i+1);

I'm pretty sure that's about as efficient as you're going to be able to make it.