Hello people,
Just a quick trivial question:
What is the result of the following code??
I can't fully understand this.Code:#define PP(n) (1 << (n))
I now that defines a new array with 'n' capacity but I can't get the result of the 1<<(n).
Hello people,
Just a quick trivial question:
What is the result of the following code??
I can't fully understand this.Code:#define PP(n) (1 << (n))
I now that defines a new array with 'n' capacity but I can't get the result of the 1<<(n).
It calculates 2**n. (2 to the nth power)
edit - it doesn't "calculate" it, it "defines" it.
Last edited by Dino; 02-05-2008 at 01:39 PM. Reason: clarification
Mainframe assembler programmer by trade. C coder when I can.
1<<0 == 0x0001
1<<1 == 0x0002
1<<16 == 0x0010
etc
it creates the number in binary form of 10000000
where there is n (binary) zeroes after 1
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
Bit off there: 1<<16 == 0x100001<<16 == 0x0010
long time; /* know C? */
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I thought so too initially, but he really isn't. Note that he shows 1 << 1 to be 0x0002. It's not the preferred format, but it is not incorrect.
Mainframe assembler programmer by trade. C coder when I can.
And 1 << 16 is 0x10000.Originally Posted by Todd Burch
--
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He used one digit to represent each byte in a 32 bit word. So, 1<<15 would have been 0x000F.
I've explained it twice - no more sticking up for him!!
Mainframe assembler programmer by trade. C coder when I can.
Yeah, the format he used sucks. I take it back. It's so wrong it's totally unclear. Either that, or or just dipped back into 16 bit harware and showed a 2-byte word.
Mainframe assembler programmer by trade. C coder when I can.
Thank you very much for all the replies!!!
That makes sense now!
Although, I should have tried a bit harder to understand it and not be impatient.
No, never
0xF in binary is 1111
So it cannot be represented in a form of 1<<n
with 1<<16 I was wrong - sorry
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
Brain fart me too. Right.
Mainframe assembler programmer by trade. C coder when I can.
The result is a macro PP() which replaces its lexical argument "n" with the expression "(1 << (n))"
