[Tutor] Struct the solution for Hex translation

Alan Gauld alan.gauld at btinternet.com
Wed Feb 21 21:51:23 CET 2007

"Johan Geldenhuys" <johan at accesstel.co.za> wrote 

> On the struct module, How can I het the binary 1's 
> and 0's of the Hex value? Let say I want to get the 
> 8 bit value of '\xe2', can I use struct to convert
> that into binary code 

No, struct converts your data into a string of bytes and 
provides a way to view a string representation of those 

But you can use bitmasks to get at the individual bits. 
(See my Using the OS topic for a box on bitwise operators 
and use of bitmasks.)

Basically you want to bitwise AND the data with a mask 
containing just a one in the 8th position
(since 1& 0 = 0 and 1& 1 = 1)

Thus 10000000 = 80 hex. So:

>>> for n in range(125,130):
...    print n,':',n&0x80
125 : 0
126 : 0
127 : 0
128 : 128     <--- the one is set so the & returns the mask
129 : 128

> so that I get 8 binary bits as a string?

See the bin() function in the sidebar in my topic for a function to
display a number in its binary form.

Alan Gauld
Author of the Learn to Program web site

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