This is a discussion on what does this mean, bitwise operator within the C++ Programming forums, part of the General Programming Boards category; im kinda confused on what exactly this means/does. Code: if (n & 1) //action n is a parameter to a ...
im kinda confused on what exactly this means/does.
n is a parameter to a recursive function and the function works, but what does the & (bitwise operator) does. From what i can understand is that when n is eventually 1 then the recursive function is called for the last time and then it returns the result. Am i right?Code:if (n & 1) //action
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Lets say that (in binary) the variable n has the following contents:
01010101010101010101010101010101
When we perform the bitwise AND of that value with 1 which is:
00000000000000000000000000000001
... we get the resulting value:
00000000000000000000000000000001
...which will evaluate to 'true' for the purposes of the if test. Basically the test is determining if the low order bit is set.
I used to be an adventurer like you... then I took an arrow to the knee.
Yes, but it really only means that when n = 0 it will endn is a parameter to a recursive function and the function works, but what does the & (bitwise operator) does. From what i can understand is that when n is eventually 1 then the recursive function is called for the last time and then it returns the result. Am i right?
n & 1 evaluates to 1 if the last bit in the number is set, and it evaluates to 0 if it is not. Since 1 means true and 0 means false, the action is performed if the last bit is set in the number. If n is unsigned, then (n & 1) will be true whenever n is odd, so whether n is eventually 1 or 3 or some other odd number doesn't matter. It will end when n is even.
so that means that 0 is considered an even number?
When no one helps you out. Call google();
n&1 is also the same as n%2
What is:Originally Posted by InvariantLoop
0000 0000
0000 0001 &
------------
?
What will happen to the loop when n=0?
Last edited by 7stud; 03-09-2006 at 05:07 PM.
>> so that means that 0 is considered an even number?
Yes, 0 is even because of the definitions of even and odd. http://en.wikipedia.org/wiki/Even_and_odd_numbers
So, if wikipedia had defined 0 as an odd number, would that affect what the loop does when n=0?
Last edited by 7stud; 03-09-2006 at 05:48 PM.
No. Your question doesn't really make sense given the context of my statement. I think you may have misunderstood my point.
0 is defined mathematically as an even number. A formal mathematical definition is that an integer i is even if it is exactly equal to 2*j where j is also an integer. All integers that are not even are odd. This definition can be expressed in a number of equivalent forms (eg a number i is even if the remainder one dividing it by 2 is zero).
Daved's link to wikipedia was for information, not a claim that life is defined by wikipedia.
An even number is a number that can be divided by 2 e.g. it doesn't leave any decimals/no remainder. Simple as that.
0/2 = 0
1/2 = 0.5
2/2 = 1
3/2 = 1.5
4/2 = 2
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