How to test whether bit is set within a flag with Python ?

MRAB python at mrabarnett.plus.com
Wed May 12 14:40:59 EDT 2010


robert somerville wrote:
> I am trying to determine how to test whether variors bits are set within 
> a byte (or larger flag) , the python 'and' and 'or' do not seem to be 
> doing what i want .. does anybody have some sample code showing how to 
> do it ??
> 
> e.g. (in "C")
> 
> unsigned char a = 6;
> 
> is 3rd bit set ??
> 
> a & 4 =,  true in this case ....
> 
'and', 'or' and 'not' are Boolean.

Python borrows its bitwise operators from C:

     &     bitwise and
     |     bitwise or
     ^     bitwise xor
     ~     bitwise not (ones' complement)
     <<    shift left
     >>    shift right

You also need to remember that Python's integers are of (virtually)
unlimited length.



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