Even and Odd Numbers

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November 22nd, 2004, 03:51 PM

kalkap

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Even and Odd Numbers

how do you differentiate even and odd numbers in ANSI C? I have to enter a bunch of numbers and then make the program count how many of those numbers were odd and how many were even.

thanks

November 22nd, 2004, 04:03 PM

Dave Sinkula

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Using the % operator you can determine whether a value is evenly divisible by two, and therefore even or odd.

Code:

if ( value % 2 )
{
   /* odd */
}

November 23rd, 2004, 07:28 AM

pflloyd

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instead of doing modulo arithmetic, which has to do division every time, just to a bit AND. This is a quicker way of doing the same check. If the least significant bit is 1 your number is odd.

Code:

if ( value & 0x01 )
{
   /* odd */
}
else
{
   /* even */
}

November 23rd, 2004, 07:42 AM

DaWei_M

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pffloyd, you apparently missed out on "EVEN AND ODD NUMBERS, THE SEQUEL." I would guess this is a dead horse....

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November 23rd, 2004, 12:40 PM

pflloyd

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aparrently I didn't. can ya fill me in?

November 23rd, 2004, 12:41 PM

L7Sqr

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just read this thread...
http://forums.devshed.com/t204206/s.html

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November 23rd, 2004, 01:44 PM

pflloyd

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ok I read that, but since some one else already answered his question, though I would improve upon it.

November 23rd, 2004, 04:18 PM

Dave Sinkula

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Quote:

Originally Posted by pflloyd

ok I read that, but since some one else already answered his question, though I would improve upon it.

Please allow me to (point to a posting that may further) expand on yours:
http://groups.google.com/groups?sel...ws1.newsguy.com

November 24th, 2004, 08:27 AM

pflloyd

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yes any good compiler should make this substitution. I've been using the ImageCraft C Compiler for an embedded system that runs on a Motorola HC12 controller, and the compiler does not make this optimization.

Even and Odd Numbers

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