How can I use an unsigned 'byte' (so it reaches 255 but is still 1 byte)

I'm doing some compression programmes for school. I've done a framework and now I'm implementing the algorithms.

My problem is that I need to work on bytes (I user array of bytes for IO purposes) and after all was developing nicely, I discovered that byte is signed and I can't do something like

byte pivot |= 128;

I neeed this because I use a vector containing "1" and "0"s that represent my coded symbol and I must apply this to a byte value.

[475 byte] By [Teo_Ga] at [2007-10-2 5:39:15]