Checking a for progression in a list of variables - php

Question

Let's say I want to check for simple mathematical progression. I understand I can do it like this:
if ($a<$b and $b<$c and $c<$d and $d<$e and $e<$f) { echo OK; }
Is there a way to do it in a more convenient way? Like so
if ($a..$f isprog(<)) { echo OK; }

Answer 1

I don 't know if I get your problem right. But propably the solution for your progression could be the SplHeap object of the SPL delivered with php.
$stack = new SplMaxHeap();
$stack->insert(1);
$stack->insert(3);
$stack->insert(2);
$stack->insert(4);
$stack->insert(5);
foreach ($stack as $value) {
echo $value . "\n";
}
// output will be: 5, 4, 3, 2, 1

Answer 2

I havent heard of something like this, but how about using simple function:
function checkProgress($vars){ //to make it easie i assume that vars can be given in an array
$result = true;
for ($i=0; $i<= count($vars); $i++){
if ($i>0 && $vars[$i] > $vars[$i-1]) continue;
$result = false;
}
return $result;
}

Answer 3

Solved it quick and dirty:
function ispositiveprogression($vars) {
$num=count($vars)-1;
while ($num) {
$result = true;
if ($vars[$num] > $vars[$num-1]) {
$num--;
}
else { $result = false; break; }
}
return $result;
}

Answer 4

Create an array of values, iterate over them and maintaining a flag that checks if the current element value is greater than / less than that of the next value. Unlike some of the solutions in this thread, this doesn't loop through the whole array. It stops looping when it discovers the first value that's not a progression. This will be a lot more faster if the operation involves a lot of numbers.
function checkIfProg($arr, $compare) {
$flag = true;
for ($i = 0, $c = count($arr); $i < $c; $i++) {
if ($compare == '<') {
if (isset($arr[$i + 1]) && $arr[$i] > $arr[$i + 1]) {
$flag = false;
break;
}
} elseif ($compare == '>') {
if (isset($arr[$i + 1]) && $arr[$i] < $arr[$i + 1]) {
$flag = false;
break;
}
}
}
return $flag;
}
Usage:
$a = 2;
$b = 3;
$c = 4;
$d = 5;
$e = 9;
$f = 22;
$arr = array($a, $b, $c, $d, $e, $f);
var_dump(checkIfProg($arr, '<')); // => bool(true)
If you want the array to be created dynamically, you could use some variable variable magic to achieve this:
$arr = array();
foreach (range('a','f') as $v) {
$arr[] = $$v;
}
This will create an array containing all the values of variables from $a ... $f.