Tricky algorithm help

[foe]

I have an array of numbers from 1 to n
1 2 3 4 ......
I need to get all the possible combinations when the first number is less than the second number ie
1
2
3
4
12
13
14
23
24
34
123
124
134
.....
1234

Thanks

[liquorvicar]

foreach ($numbers as $number) {
  $temp = strval($number);
  $temp = (strlen($temp)<2 ? '0'.$temp : $temp);
  $first = $temp{0};
  $second = $temp{1};
  if (intval($first)<intval($second)) {
    echo($number.'<br>');
  }
}

or do you mean "where each digit is higher than the preceding digit"?

foreach ($numbers as $number) {
  $temp = strval($number);
  $last = 0;
  $flag = 1;
  for ($i=0;$i++;$i<strlen($temp)) {
    if ($last>=$temp{$i}) {
      $flag = 0;
    }
    $last = $temp{$1};
  }
  if ($flag) {
    echo($number.'<br>');
}

[foe]

<?
$numbers[] = 1;
$numbers[] = 2;
$numbers[] = 4;
$numbers[] = 5;

foreach ($numbers as $number) {
$temp = strval($number);
$last = 0;
$flag = 1;
for ($i=0;$i++;$i<strlen($temp)) {
if ($last>=$temp{$i}) {
$flag = 0;
}
$last = $temp{$i};
}
if ($flag) {
echo($number.'<br>');
}
}

for the printout I get
1
2
4
5

any idea why?

[liquorvicar]

because that's what you asked for in your original post!

[laserlight]

You could try this:

<?php
$numbers = range(1, 5);
$count = count($numbers);
for ($i = 0; $i < $count; $i++) {
	echo $numbers[$i] . ", ";
	for ($j = $i + 1; $j < $count; $j++) {
		$temp = $numbers[$i];
		for ($k = $j; $k < $count; $k++) {
			$temp .= $numbers[$k];
			echo $temp . ", ";
		}
	}
	echo "<br />\n";
}
?>

EDIT:
or more likely, something like this:

<?php
$numbers = range(1, 5);
$count = count($numbers);
$array = array();
for ($i = 0; $i < $count; $i++) {
	$array[] = $numbers[$i];
	for ($j = $i + 1; $j < $count; $j++) {
		$temp = $numbers[$i];
		for ($k = $j; $k < $count; $k++) {
			$temp .= $numbers[$k];
			$array[] = $temp;
		}
	}
}
sort($array);
echo implode("<br />\n", $array);
?>

Incidentally, did it occur to you that this isnt a database specific question?

[foe]

THANKS !!!!!!

[foe]

But its for a database ...

Also the code above skips 124 and 135 etc ... anyways around it?

[laserlight]

hmm... I made a mistake in my algorithm.
Here's the corrected version, though unfortunately it is recursive rather than iterative:

<?php
function genNum(&$ret_array, $seed_array, $count, $start, $num) {
	for ($i = $start; $i < $count; $i++) {
		$ret_array[] = $temp = $num . $seed_array[$i];
		genNum($ret_array, $seed_array, $count, $i + 1, $temp);
	}
}

$numbers = range(1, 5);
$count = count($numbers);
$array = array();
genNum($array, $numbers, $count, 0, '');
sort($array);
echo implode("<br />\n", $array);
?>