Calling all coders. Moving around a counter ??

Johnnytoxic · 25 Mar 2008 at 20:48

In php I have a count that goes 0,1,2 then goes back to 0.

If the count was on 1 how would i make it go back two places so that it would end up on 2 ??

any ideas.

|Ric| · 25 Mar 2008 at 21:01

High level approach, as I am not that up with PHP, create a counter object, that has a plus and minus method and do all the wrapping of the counter in that

From memory PHP is OOP to a certain extend right? Otherwise the code is going to be quite messy.

Una · 25 Mar 2008 at 21:06

Use mod 3 arithmetic, if its on 1 then just add 2 to it = 0.

|Ric| · 25 Mar 2008 at 21:08

Una said:
Use mod 3 arithmetic, if its on 1 then just add 2 to it = 0.

Well now I feel stupid! (I'll pretend mine is slightly superior as there is no worry of overflow.)

Una · 25 Mar 2008 at 21:10

|Ric| said:
Well now I feel stupid! (I'll pretend mine is slightly superior as there is no worry of overflow.)

OO programming does retarded coders tbh.

Johnnytoxic · 25 Mar 2008 at 21:14

Can I be cheeky and ask for an example. Googles bringing up lots of things

Inquisitor · 25 Mar 2008 at 23:58

|Ric| said:
High level approach, as I am not that up with PHP, create a counter object, that has a plus and minus method and do all the wrapping of the counter in that

From memory PHP is OOP to a certain extend right? Otherwise the code is going to be quite messy.

What :/

You just need to use modular arithmetic, specifically the % (modulus) operator:

Code:

$counter = ($counter + $increment) % 3;

Edit: this is more robust:

Code:

$counter = ($counter + $increment + ceil(abs($increment) / 3) * 3) % 3;

The ceil(abs($increment) / 3) * 3 bit just makes sure whatever is in the brackets is positive, regardless of what $increment is, so that you can add or subtract and it'll still work.