[Tutor] binary data as string?

[Alan Gauld]

> When one does 'bitwise' movements over data in strings 
> it is actually moving 'characterwise', correct?

No, characters are bytesize, bitwise means looking at 
the individual bits. Usually this is done by taking a 
byte and applying a "mask" to the byte to determine 
the value.

For example applying a bitwise AND of 0x01 to a byte 
will return the rightmost bit, by "leftshifting" the 
mask and repeating we can see each individual bit in turn:

mask = 1
data = 42
for n in range(8):
   print (data & mask) and 1 or 0,
   mask = mask << 1

Will print out the bit pattern of 42...

HTH,

Alan G
Author of the Learn to Program web tutor
http://www.freenetpages.co.uk/hp/alan.gauld