Computer Science Canada

Odd or Even Integer?

Author:

kaotickid [ Tue Mar 18, 2008 8:43 pm ]

Post subject:

Odd or Even Integer?

I'm wondering if there's a code out there to distinguish between an odd and even integer. This is a problem from the Turing .PDF (Chapter 14, Question 17), it's pretty much done but I just need to put the code that distinguishes whether an integer is even or odd. Thanks Very Happy

code:

var numbers : array 1 .. 10 of int

for i : 1 .. 10
get numbers (i)
end for

for i : 1 .. 10
%How to distinguish between odd or even.
put numbers (i), "is an odd number."
%How to distinguish between odd or even.
put numbers (i), "is an even number."
end for

Author:	CodeMonkey2000 [ Tue Mar 18, 2008 8:47 pm ]
Post subject:	RE:Odd or Even Integer?
Use the modulus operation( the % sign). It gives the remainder of two integer. (eg 3%2 =1 since 2*2=2 and we have a remainder of 1).

Author:

A.J [ Tue Mar 18, 2008 8:48 pm ]

Post subject:

Re: Odd or Even Integer?

there's a function in math called 'mod' thats also recognized in turing.
x mod y gives the remainder when x is divided by y.
so 17 mod 5 will give 2, since 17/5= 3 remainder 2.

so for distinguishing between odd and even, just take the number mod 2.
if it is 0 (anything divisible by 2 always gives 0, since there isn't any remainder), its even.
Otherwise if it is 1 (if it is not divisible by 2 then it has a remainder of 1), its odd!
so:

Turing:

var x:int
put "Enter a number:"..
get x
if x mod 2=0 then
put x," is a even number"
else
put x," is an odd number"
end if

Hope this helped Very Happy

A.J

EDIT: CodeMonkey2000 beat me to it. Oh darn Crying or Very sad

Author:	kaotickid [ Tue Mar 18, 2008 8:52 pm ]
Post subject:	Re: Odd or Even Integer?
Haha A.J, but thanks to both of you, A.J and CodeMonkey Well my questions is answered

Author:

Nyrd [ Tue Mar 18, 2008 8:54 pm ]

Post subject:

Re: Odd or Even Integer?

code:

var number : int := 5

if number mod 2 = 0 then
put "Even"
else
put "odd"
end if
% This will display "odd"

That should do it Very Happy

In case you're wondering, "mod" is the modulo function. It essentially finds the remainder when you divide the number by 2 (in this case).
--Remember, if you divide a number by 2 and there is no remainder it must be even!--

Author:	Nyrd [ Tue Mar 18, 2008 8:56 pm ]
Post subject:	Re: Odd or Even Integer?
Wow, I was beat to it by two people . . . For shame . . .

Author:

agnivohneb [ Tue Mar 18, 2008 9:07 pm ]

Post subject:

Re: Odd or Even Integer?

A.J @ Tue Mar 18, 2008 8:48 pm wrote:

Turing:

var x:int
put "Enter a number:"..
get x
if x mod 2=0 then
put x," is a even number"
else
put x," is an odd number"
end if

You could also use the div function and instead of equaling 0 it equals 1.

Turing:

var x:int
put "Enter a number:"..
get x
if x div 2=1 then % Note the div and the 1
put x," is a even number"
else
put x," is an odd number"
end if

Author:

HeavenAgain [ Tue Mar 18, 2008 9:15 pm ]

Post subject:

Re: RE:Odd or Even Integer?

CodeMonkey2000 @ Tue Mar 18, 2008 9:47 pm wrote:

(eg 3%2 =1 since 2*2=2 and we have a remainder of 1).

2*2 = 2?

agnivohneb @ Tue Mar 18, 2008 10:07 pm wrote:

You could also use the div function and instead of equaling 0 it equals 1.

yes you could use div to check if its odd or even, but in your example .... well, you should take another look at it

code:

if x div 2 = 1 then
put "even"
else
put "odd"

something is odd here

Author:	agnivohneb [ Tue Mar 18, 2008 9:21 pm ]
Post subject:	RE:Odd or Even Integer?
ummmmm ... think ... think ... I give up!

Author:

richcash [ Tue Mar 18, 2008 9:24 pm ]

Post subject:

Re: Odd or Even Integer?

Bitwise 'and' is a bit faster than modulus I think.

code:

if x & 1 then
put "even"
else
put "odd"
end if

agnivohneb, try putting in any even number other than 2 in your code. See the problem?

Author:

Saad [ Tue Mar 18, 2008 9:28 pm ]

Post subject:

Re: Odd or Even Integer?

If you want to be crazy and go with some mutual recursion Wink

Turing:

forward fcn isEven (n : int) : boolean
forward fcn isOdd (n : int) : boolean

body fcn isEven
if (n = 0) then
result true
else
result isOdd (n - 1)
end if
end isEven

body fcn isOdd
if (n = 0) then
result false
else
result isEven (n - 1)
end if
end isOdd

put isOdd (1)
put isEven (1)

Author:	agnivohneb [ Tue Mar 18, 2008 9:29 pm ]
Post subject:	RE:Odd or Even Integer?
Wait! ... Ha! I got it. I reject my last comment. I know what the problem is now. It is not accurate.

Author:	A.J [ Tue Mar 18, 2008 9:42 pm ]
Post subject:	Re: Odd or Even Integer?
nice richcash bits are the way to go. as for you saad.......lets just say forget about mutual recursion for now, shall we

Author:	CodeMonkey2000 [ Wed Mar 19, 2008 2:56 pm ]
Post subject:	RE:Odd or Even Integer?
Wow talk about overkill.......

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