Regular Expression

Ben643 · 31 Jul 2009 at 18:45

I'm trying to learn about regular expressions at the moment but just can't get my head around them!

I need to find a way of making sure a 4 digit number contains only the numbers 0, 5 and 9... so it must have all 3 and only all 3 numbers within the 4 digits (obviously any one of the 3 can be repeated to make the 4 digits total).

Hope that makes sense. I'm sure there was a much easier way of explaining it!

Any help appreciated.

Mickey · 31 Jul 2009 at 20:15

^[059]{4}$

robmiller · 31 Jul 2009 at 20:41

Mickey said:
^[059]{4}$

That will match "5555", which doesn't fit his criteria.

Ben643 · 31 Jul 2009 at 20:58

Yeah, I did try that earlier. It brings up false positives as robmiller says unfortunately

So I just need a way of saying "0 AND 5 AND 9" instead of OR. Google doesn't seem to help on this occasion though!

LiE · 31 Jul 2009 at 21:04

What language are you writing this in? Maybe better to do this with conditional statements and some regex.

Ben643 · 31 Jul 2009 at 21:48

msm722 said:
What language are you writing this in? Maybe better to do this with conditional statements and some regex.

PHP at the moment... but I could do it in Java or C# as well, I'm just doing it to learn about regular expressions really, nothing important.

Mickey · 31 Jul 2009 at 23:22

robmiller said:
That will match "5555", which doesn't fit his criteria.

Whoops, didn't see that bit

Mickey · 31 Jul 2009 at 23:45

It's a bit (very) dirty, but you could:

^(0059|0095|0509|0559|0590|0595|0599|0905|0950|0955|0959|0995|5009|5059|5090|5095|5099|5509|5590|5900|5905|5909|5950|5990|9005|9050|9055|9059|9095|9500|9505|9509|9550|9590|9905|9950){1}$

Ben643 · 1 Aug 2009 at 02:07

Haha, I don't mind a bit of dirty programming once in a while... but that's a bit too far for my liking!

I've done it like this for now:

if(preg_match("/^[059]{4}$/",$j)){
if(stristr($j, '0') && stristr($j, '5') && stristr($j, '9')){
echo $j . "<br />";
}
}

Even that's a bit dirty, but I think it's working.