posted 11 years ago
All sorts of obscure ways you can use them in practice. About a year back we had discussion about how to implement the sort of LED lamps which have seven components in, to show numbers on screen. One way is to have different binary numbers which correspond to the different displays so "8" would come out as 01111111 (it is the only number where all seven bars are illuminated). To find out whether bar 0 is illuminated, you can "and" the number with 00000001.
A typical AND calculation follows:
10101010 AND
00000001
________
00000000
This particular sum gives 0 throughout because there are no pairs of bits with 1 in both, whereas the following doesn't give 0:
10101011 AND
00000001
________
00000001
Or gives 1 if either or both the bits at a particular location are 1. copying and pasting gives:
10101010 OR
00000001
________
10101011
10101011 OR
00000001
________
10101011
There is also XOR (^) which gives 1 if the two bits at the same location are different.
10101010 XOR
00000001
________
10101011
10101011 XOR
00000001
________
10101010
As you have been told  means OR & means AND (and ^ means XOR). a &= b; is shorthand for a = a & b;
CR
A typical AND calculation follows:
10101010 AND
00000001
________
00000000
This particular sum gives 0 throughout because there are no pairs of bits with 1 in both, whereas the following doesn't give 0:
10101011 AND
00000001
________
00000001
Or gives 1 if either or both the bits at a particular location are 1. copying and pasting gives:
10101010 OR
00000001
________
10101011
10101011 OR
00000001
________
10101011
There is also XOR (^) which gives 1 if the two bits at the same location are different.
10101010 XOR
00000001
________
10101011
10101011 XOR
00000001
________
10101010
As you have been told  means OR & means AND (and ^ means XOR). a &= b; is shorthand for a = a & b;
CR
posted 11 years ago
I would check out Bruce Eckel's Thinking in Java for a good look at operators.
It is a great book and available free online. (easily googled)
It is a great book and available free online. (easily googled)
M Easter
Software Composer  http://codetojoy.blogspot.com
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