Determining if a variable is even or odd?

Question

Hello. If I have a variable is a whole number, how can I set up and if statement to see of the variable is even or odd? such as:

 if (TEST==odd ){something};
 if (TEST==even){something else};

Thanks

Answer 1

Best Answer

Answer by Tseng · Mar 08, 2012 at 02:28 AM

Use modulo operator

 if(test%2==0) // Is even, because something divided by two without remainder is even, i.e 4/2 = 2, remainder 0
 if(test%2==1) // Is odd, because something divided by two with a remainder of 1 is not even, i.e. 5/2 = 2, remainder 1

Add comment · Show 13 · Share

YunLee · Jan 24, 2014 at 12:44 PM 0

Share

what if a dividend is negative? He said the variable is a whole number.

MrVerdoux · Jan 24, 2014 at 12:46 PM 0

Share

Then just use $$anonymous$$athf.Abs before.

YunLee · Jan 24, 2014 at 12:54 PM 0

Share

Very simple, thanks.

if(test%2==1||test%2==-1) Can I use this too?

Tseng · Jan 24, 2014 at 01:01 PM 0

Share

Just use test%2==0 for even or test%2!=0 for uneven. However, this only works in this special case or if you want deter$$anonymous$$e if a number is fully dividable through another number or not.

MrVerdoux · Jan 24, 2014 at 01:35 PM 0

Share

in the strange case anyone wanted to see if a float is odd or even, first I would cast it to an int. It makes more sense to me, but some people might still prefer the strange case in which a float is perfectly dividable.

andibuss23 MrVerdoux · Feb 24, 2021 at 06:30 PM 0

Share

Hi, in my case its very useful because im making a runner where the player can only move to certain positions. Those positions are even coordinates and i only want the player to move when they are in an even position, otherwise they could move in the middle of the lines.

Show more comments

Answer 2

Answer by firemyst · Jan 16, 2014 at 01:12 PM

Here’s a blog article which benchmarks quite a few ways to test if a number is odd or even.

Surprisingly, the fastest way appears to be the modulus % operator, even out performing the bitwise ampersand &, as follows:

 for (int x = 0; x < NumberOfNumbers; x++)
 {
         if (x % 2 == 0)
                total += 1; //even number
         else
                total -= 1; //odd number
 }

Definitely worth a read for those that are curious.

Add comment · Share

Determining if a variable is even or odd?

2 Replies

Follow this Question

Related Questions