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I couldn't think of a good title, but I was hoping to get some help with a script that will calculate and display all possible number combinations of a 3 (or 4) digit number where the number of digits is 3, they are non repeating, and is limited to the numbers 1 - 5.
I imagine this would not be too big of a script, but how to do this is not coming to mind.
Do you just want one at random? This will work for that:
Of course you can chop that at 3 characters long if you want.PHP Code:function randnumstr() {
for($i=1;$i<5;$i++) {
$a[] = $i;
}
shuffle($a);
return implode('',$a);
}
But if you want to actually systematically display all of them, then you should go through a loop.
There are two ways to do this: generate all possible numbers and eliminate those that have repeated digits; or generate only the valid ones. The first is easier to program, the second might be a little more efficient.
See if that gets you started. If not, I could probably write it for you.
Thank you for that. How would it look if you wanted to gather all of the combinations and listed them sequentially. A 3 digit combination is one idea, but what about 4 or 5? Most importantly, how would it look if it were not in a function? I mention that because I am terrible with functions in php. In javascript they are easier for me to understand for some reason.
Your code is giving me a good starting point and it is helping me to see how it would look.
There is no real application for this script. It's just a fun exercise.
The function above is irrelevant. You could just take that wrapper off and use echo instead of return. Functions are just convenient.
For the other, you'd need to do a loop. It would get even more complicated if you wanted everything from 1-5 digits (rather than only 5 digits). You're going to end up with something like 4 embedded loops.
Alternatively you could use a recursive function. That'll be faster.
Here's a probably working example (untested):
PHP Code:$numbers = array();
function numberstuff($length,$prefix) { //this is ALL you need if you want every possible combination
if (!is_numeric($length)||$length<1||round($length)!=$length) { return false; }
for($i=0;$i<10;$i++) {
if ($length==1) {
numberstuff($length-1,$prefix.$i);
}
else {
$GLOBALS['numbers'][] = $prefix.$i . "\n";
}
}
}
function numberstuff2($length) { //this function strips out any numbers with duplicated numbers in them-- note that the max length now will be 9, because 10+ will contain duplicates and be removed
numberstuff($length);
$numbers = $GLOBALS['numbers'];
$GLOBALS['numbers'] = array(); //reset external storage array for later if needed
foreach($numbers as $nkey=>$n) {
for($i=0;$i<10;$i++) {
if (substr_count($n,$i)>1) {
unset($numbers[$nkey]);
}
}
}
sort($numbers); //clean up indices, etc.
return $numbers;
}
$mynumbers = numberstuff2(5);
print_r($mynumbers);
cool, thanks :)
I'll give it a whirl.
After looking at your script some more I wrote this:
I know it doesn't lend itself too well to versatility though.PHP Code:<?php
$a=122;
$b=array();
while ($a<543){$a++;
$a1=substr($a,0,1);
$a2=substr($a,1,1);
$a3=substr($a,2,1);
if ($a3==6){$a2++;$a3=1;}
if ($a2==6){$a1++;$a2=1;}
$a="$a1"."$a2"."$a3";
if ($a>543)break;
if ($a1!=$a2 and $a1!=$a3 and $a2!=$a3)$b[]=$a;
}
echo"<pre>";
print_r($b);
echo"</pre>";
?>
Haha. That's easier to deal with.
By chance, I'm working on a project tonight that needs a code like mine above. I need to find all possible combinatorial possibilities. It's very confusing. I'll try to adapt what I wrote above to make it work (and as I do so, I'll debug what I wrote, if there are problems).
Well, that's hilarious. I used == instead of >. One typo. Now it works perfectly. Confusing to debug though... it was just giving 0-9 :p
(I updated a bit more too, mostly the output format. Now it returns a plain array of all the numbers.)
That works.PHP Code:<?php
$numbers = array();
function numberstuff($length,$prefix='') { //this is ALL you need if you want every possible combination
if (!is_numeric($length)||$length<1||round($length)!=$length) { return false; }
for($i=0;$i<10;$i++) {
if ($length>1) {
numberstuff($length-1,($prefix.$i));
}
else {
$GLOBALS['numbers'][] = ($prefix.$i);
}
}
}
function numberstuff2($length) { //this function strips out any numbers with duplicated numbers in them-- note that the max length now will be 9, because 10+ will contain duplicates and be removed
numberstuff($length);
$numbers = $GLOBALS['numbers'];
$GLOBALS['numbers'] = array(); //reset external storage array for later if needed
foreach($numbers as $nkey=>$n) {
for($i=0;$i<10;$i++) {
if (substr_count($n,$i)>1) {
echo '1';
unset($numbers[$nkey]);
}
}
}
sort($numbers); //clean up indices, etc.
return $numbers;
}
$mynumbers = numberstuff2(4);
print_r($mynumbers);
?>
Yep, it is working for me now too. It was not working for me earlier, but I figured that was due to my lack of understanding of how to use php functions ;).
I noticed you left in a placeholder output in the first line of your output with "Array" listed at the end. Fun to try out by the way.
Oops. Debug info now edited out.
You still have a little bit left :p
EDIT: Number of combinations = multiplying the highest numbers together. The number of numbers multiplied together is the same as the number of digits in the result. 4 digit result using 10 digits = 10*9*8*7=5040.
This reminds me of some algebra equation from my distant past. I am sure the equation I posted is flawed in some way, but it is interesting.
EDIT: Found it ref.
The number is easy enough to calculate mathematically, but actually finding all of the permutations directly without overgenerating* involves a ridiculous recursive function. It's a very hard task, although many other things aren't so hard.
(*Of course you can overgenerate and remove the extras as needed.)
It essentially needs to program itself. It's easy enough to write a set of embedded loops that will do it for a specific length, but allowing that to be any arbitrary length (as a parameter) is where it gets tricky.