help with converting javascript function to php

Question

My javascript isnt so great, but i found a brilliant looking function here

I'm not sure what to do with this bit:

var ranges = [], rstart, rend;

full function:

function getRanges(array) {
 var ranges = [], rstart, rend;
 for (var i = 0; i < array.length; i++) {
 rstart = array[i];
 rend = rstart;
 while (array[i + 1] - array[i] == 1) {
 rend = array[i + 1]; // increment the index if the numbers sequential
 i++;
 }
 ranges.push(rstart == rend ? rstart+'' : rstart + '-' + rend);
 }
 return ranges;
}
getRanges([2,3,4,5,10,18,19,20]);
// returns ["2-5", "10", "18-20"]
getRanges([1,2,3,5,7,9,10,11,12,14 ]);
// returns ["1-3", "5", "7", "9-12", "14"]
getRanges([1,2,3,4,5,6,7,8,9,10])
// returns ["1-10"]

• Felix Kling: There is nothing really JS specific in it, it is nearly the same in PHP. All variables have to start with $, array initialization is array(), array.length translates to count($array), array.push is either $array[]= or array_push($array, $value) and concatenation goes with . instead of +.
• webbiedave: Which parts are you having trouble with? This is a place to get help with your programming. Not to get free labor.
• Haroldo: i was confused by this bit, particularly: var ranges = [], rstart, rend
• dusoft: $ranges=array(); - you don't have to define beginning and end of an array in php.
• Austin Fitzpatrick: "var ranges = [], rstart, rend;" is just saying "make three variables, one called ranges that is an array and two called "rstart" and "rend".

Answer 1

It's almost exactly the same in PHP.

<?php
function getRanges($array){
 $ranges = array();
 for($i = 0; $i < count($array); $i++){
 $rstart = $array[$i];
 $rend = $rstart;
 while($array[$i + 1] - $array[$i] == 1){
 $rend = $array[$i + 1]; //incremenent the index if sequential
 $i++;
 }
 $ranges[] = ($rstart == $rend) ? $rstart.'' : $rstart . '-' . $rend;
 }
 return $ranges;
}
var_dump(getRanges(array(2,3,4,5,10,18,19,20)));
/*
array(3) {
 [0]=>
 string(3) "2-5"
 [1]=>
 string(2) "10"
 [2]=>
 string(5) "18-20"
}
*/
?>

• webbiedave: ... or maybe it is a place for that.
• Austin Fitzpatrick: Yeah, I thought about not answering but sometimes it helps to have someone spell it out for you a couple times when you're new. It wasn't much "work" for me, find and replace the variable names with a "$" infront and replace "+" with "." in a few places.
• Haroldo: Thanks Austin, very kind of you to take the time I'll be sure to be less lazy with questions in future! thanks again
• webbiedave: Yeah, the code is so analogous it probably only took a minute.

Answer 2

Just for your information:

var ranges = [], rstart, rend;

just declares three variables ranges, rstart and rend. ranges is also initialized as an empty array.
It is the same as

var ranges = [];
var rstart;
var rend;

In PHP you don't necessarily have to declare the variables beforehand.