even or odd

**Richard Bos** · Mar 19 '08, 03:05 PM

Re: even or odd

melsayid <melsayid@gmail .comwrote:

The program always shows that the input is odd.

No, it doesn't. Try entering 0.

You might want to look up the modulo operator, BTW.

Richard

**Morris Dovey** · Mar 19 '08, 03:15 PM

Re: even or odd

melsayid wrote:

>
The program always shows that the input is odd.
>
int main ()
{
int n, d;
>
printf ("Enter a Number: ");
scanf ("%d", &n);
d=1;
if (d==n)
{
printf ("The number is odd\n");
}
else if (d < n)
{
for (; d<n; d+=2);
printf ("The number is odd\n");
}
else
{
printf ("The number is even\n");
}
>

This should work for twos complement machines:

#include <stdio.h>
int main(void)
{ int n;
printf ("Enter a Number: ");
scanf ("%d", &n);
printf("n is %s\n",(n & 1)?"odd":"even" );
return 0;
}

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA

http://www.iedu.com/DeSoto/

**melsayid** · Mar 19 '08, 03:15 PM

Re: even or odd

On Mar 19, 4:57 pm, r...@hoekstra-uitgeverij.nl (Richard Bos) wrote:

melsayid <melsa...@gmail .comwrote:

The program always shows that the input is odd.

>
No, it doesn't. Try entering 0.
>
You might want to look up the modulo operator, BTW.
>
Richard

Try entering 2 or any higher even number.

--
Mustafa Zaza

**Richard Tobin** · Mar 19 '08, 03:25 PM

Re: even or odd

In article <6927a02c-a8e1-44c8-979d-4c00d949b724@e2 3g2000prf.googl egroups.com>,
melsayid <melsayid@gmail .comwrote:

else if (d < n)
{
for (; d<n; d+=2);
printf ("The number is odd\n");
}

What is the point of the loop here? You don't test anything after
it; you just print "The number is odd".

-- Richard
--
:wq

**Richard Tobin** · Mar 19 '08, 03:35 PM

Re: even or odd

In article <47E12D13.7AC26 60B@iedu.com>,
Morris Dovey <mrdovey@iedu.c omwrote:

>This should work for twos complement machines:
>
>#include <stdio.h>
>int main(void)
>{ int n;
printf ("Enter a Number: ");
scanf ("%d", &n);
printf("n is %s\n",(n & 1)?"odd":"even" );
return 0;
>}

It will work for non-negative ints regardless of whether the machine
uses twos complement.

-- Richard
--
:wq

**melsayid** · Mar 19 '08, 03:35 PM

Re: even or odd

On Mar 19, 5:19 pm, rich...@cogsci. ed.ac.uk (Richard Tobin) wrote:

In article <6927a02c-a8e1-44c8-979d-4c00d949b...@e2 3g2000prf.googl egroups.com>,
>
melsayid <melsa...@gmail .comwrote:

else if (d < n)
{
for (; d<n; d+=2);
printf ("The number is odd\n");
}

>
What is the point of the loop here? You don't test anything after
it; you just print "The number is odd".
>
-- Richard
--
:wq

I've removed the semicolon and it still doesn't work probably.
Here is how I thought about it,
*The input is n
1-Equals the d with 1
2-Check if the n is equal to d, if yes it prints that the number is
odd
3-If not it checks if the d is less with n, if not it keeps on adding
+2 to the d till it's equal to the value of the n then output that
it's odd
4-Anything else should output that the input is even

@Morris
It works for me, but I want to figure out what's wrong with my code.
Also I don't understand your code, I just started learning C.

--
Mustafa El Sayid

**Richard Tobin** · Mar 19 '08, 03:35 PM

Re: even or odd

In article <cc4b6752-b7cb-40de-9025-48b41d39041f@e2 3g2000prf.googl egroups.com>,
melsayid <melsayid@gmail .comwrote:

for (; d<n; d+=2);
printf ("The number is odd\n");

>3-If not it checks if the d is less with n, if not it keeps on adding
>+2 to the d till it's equal to the value of the n then output that
>it's odd

Suppose n is 8. You add 2 to d until it's greater than or equal to n.
In this case, that will happen when d is 9. But you still print out
that n is odd! You don't do anything different depending on whether d
stopped at n or went one past it.

-- Richard
--
:wq

**Morris Dovey** · Mar 19 '08, 03:35 PM

Re: even or odd

Richard Tobin wrote:

>
In article <47E12D13.7AC26 60B@iedu.com>,
Morris Dovey <mrdovey@iedu.c omwrote:

This should work for twos complement machines:

#include <stdio.h>
int main(void)
{ int n;
printf ("Enter a Number: ");
scanf ("%d", &n);
printf("n is %s\n",(n & 1)?"odd":"even" );
return 0;
}

>
It will work for non-negative ints regardless of whether the machine
uses twos complement.

You noticed that, eh?

:-D

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA

http://www.iedu.com/DeSoto/

**melsayid** · Mar 19 '08, 03:35 PM

Re: even or odd

On Mar 19, 5:35 pm, rich...@cogsci. ed.ac.uk (Richard Tobin) wrote:

In article <cc4b6752-b7cb-40de-9025-48b41d390...@e2 3g2000prf.googl egroups.com>,
>
melsayid <melsa...@gmail .comwrote:

for (; d<n; d+=2);
printf ("The number is odd\n");

3-If not it checks if the d is less with n, if not it keeps on adding
+2 to the d till it's equal to the value of the n then output that
it's odd

>
Suppose n is 8. You add 2 to d until it's greater than or equal to n.
In this case, that will happen when d is 9. But you still print out
that n is odd! You don't do anything different depending on whether d
stopped at n or went one past it.
>
-- Richard
--
:wq

Ok, it's working now.
Thanks.

--
Mustafa El Sayid

**Kenneth Brody** · Mar 19 '08, 03:45 PM

Re: even or odd

melsayid wrote:

>
The program always shows that the input is odd.

Not "always", just "for any positive number". (See also Richard Bos'
reply.)

int main ()
{
int n, d;
>
printf ("Enter a Number: ");
scanf ("%d", &n);

You should probably check for failure here, but you can get away
without it for simple test cases where you are entering the data.

d=1;
if (d==n)
{
printf ("The number is odd\n");
}
else if (d < n)

This statement will be true for any "n" greater than 1.

{
for (; d<n; d+=2);

Here, you simply increment d by 2 until it is at least equal to n.
Consider, however, how long your program will run if you enter a
number such as 2000000000. Also consider that this may never
terminate if you enter 2147483647.

<pedant>
Note my use of the word "may" in the preceding sentence. :-)
</pedant>

printf ("The number is odd\n");

And then unconditionally print "The number is odd".

}
else

Only zero or negative numbers will ever get here.

{
printf ("The number is even\n");

And then unconditionally print "The number is even".

}

Look up the modulo operator -- % -- as it will suit your needs.

--
+-------------------------+--------------------+-----------------------+
| Kenneth J. Brody | www.hvcomputer.com | #include |
| kenbrody/at\spamcop.net | www.fptech.com | <std_disclaimer .h|
+-------------------------+--------------------+-----------------------+
Don't e-mail me at: <mailto:ThisIsA SpamTrap@gmail. com>

**Robbie Hatley** · Mar 19 '08, 08:25 PM

Re: even or odd

"melsayid" sed:

The program always shows that the input is odd.

No it doesn't.

It prints
"even" for all numbers < 1
"odd" for all numbers >= 1

Which, of course, makes no sense whatsoever.

int main ()
{
int n, d;
>
printf ("Enter a Number: ");
scanf ("%d", &n);
d=1;
if (d==n)
{
printf ("The number is odd\n");
}
else if (d < n)
{
for (; d<n; d+=2);
printf ("The number is odd\n");
}
else
{
printf ("The number is even\n");
}

Write it in English first. Here's what you just wrote, translated into
plain English:

if d is 1 or greater, print "odd"
else print "even"

Does it make any sense in English? No. So it won't make any sense in C,
either!

Look-up "modulo" in a math book. Then look-up "modulo" in a C book.
(Hint: its the "%" operator.)

Then ask yourself, "what do the words 'even' and 'odd' mean?".
(Hint: it has to do with whether a number is divisible by 2.)

Then ask yourself, "what is the relationship betwen 'divisibility' and
'modulo'?"

I could easily re-write your program for you to correctly print
"odd" or "even", but I won't be a prick and spoil the fun you
could have by forcing yourself to learn these things for yourself.

--
Cheers,
Robbie Hatley
lonewolf aatt well dott com
www dott well dott com slant user slant lonewolf slant

**Kenneth Brody** · Mar 20 '08, 01:35 PM

Re: even or odd

melsayid wrote:

>
On Mar 19, 5:35 pm, rich...@cogsci. ed.ac.uk (Richard Tobin) wrote:

In article <cc4b6752-b7cb-40de-9025-48b41d390...@e2 3g2000prf.googl egroups.com>,

melsayid <melsa...@gmail .comwrote:

for (; d<n; d+=2);
printf ("The number is odd\n");
>3-If not it checks if the d is less with n, if not it keeps on adding
>+2 to the d till it's equal to the value of the n then output that
>it's odd

Suppose n is 8. You add 2 to d until it's greater than or equal to n.
In this case, that will happen when d is 9. But you still print out
that n is odd! You don't do anything different depending on whether d
stopped at n or went one past it.

-- Richard
--
:wq

>
Ok, it's working now.
Thanks.

Could you post your updated "working" code?

Have you considered the ramifications of your logic should the
person enter 2000000000 (or 2147483647) as the number?

--
+-------------------------+--------------------+-----------------------+
| Kenneth J. Brody | www.hvcomputer.com | #include |
| kenbrody/at\spamcop.net | www.fptech.com | <std_disclaimer .h|
+-------------------------+--------------------+-----------------------+
Don't e-mail me at: <mailto:ThisIsA SpamTrap@gmail. com>

**Mahesh** · Mar 21 '08, 06:05 AM

Re: even or odd

On Mar 20, 6:19 pm, Kenneth Brody <kenbr...@spamc op.netwrote:

melsayid wrote:
>

On Mar 19, 5:35 pm, rich...@cogsci. ed.ac.uk (Richard Tobin) wrote:

In article <cc4b6752-b7cb-40de-9025-48b41d390...@e2 3g2000prf.googl egroups.com>,

>

melsayid <melsa...@gmail .comwrote:
for (; d<n; d+=2);
printf ("The number is odd\n");
3-If not it checks if the d is less with n, if not it keeps on adding
+2 to the d till it's equal to the value of the n then output that
it's odd

>

Suppose n is 8. You add 2 to d until it's greater than or equal to n.
In this case, that will happen when d is 9. But you still print out
that n is odd! You don't do anything different depending on whetherd
stopped at n or went one past it.

>

-- Richard
--
:wq

>

Ok, it's working now.
Thanks.

>
Could you post your updated "working" code?
>
Have you considered the ramifications of your logic should the
person enter 2000000000 (or 2147483647) as the number?
>
--
+-------------------------+--------------------+-----------------------+
| Kenneth J. Brody |www.hvcomputer .com| #include |
| kenbrody/at\spamcop.net |www.fptech.com | <std_disclaimer .h|
+-------------------------+--------------------+-----------------------+
Don't e-mail me at: <mailto:ThisIsA SpamT...@gmail. com>- Hide quoted text -
>
- Show quoted text -

Lets keep it simple

check for the least significant bit of the number, if its 0 then its
even else its odd.
something like

if(num & 0x1)
printf(" ODD \n");
else
printf(" EVEN \n");

happy coding

**santosh** · Mar 21 '08, 05:05 PM

Re: even or odd

Mahesh wrote:

<code to check host endianness>

Lets keep it simple
>
check for the least significant bit of the number, if its 0 then its
even else its odd.
something like
>
if(num & 0x1)
printf(" ODD \n");
else
printf(" EVEN \n");
>
happy coding

But this won't detect mixed-endian machines.

even or odd

even or odd

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