explode a string

Fun question Tony! That's a tricky one for me and I'm still new to this too but I think it can be done without even needing an array of elements. As long as the chemical formula was formatted correctly using upper and lower case characters could you read through the formula, letter by letter, stopping prior to reaching the next capital letter. For example when I look at NaNO3 I know that Na is one element, N is the next, and O3 is the next as long as upper and lower case is used correctly. Perhaps run it through a loop that stops when it gets to the end of the formula. Hmmm.
The following devolves into pseudocode in the while loop at the end sorry!:

// load chemical formula into a variable:
$chemical_formula = 'NaNO3';

// get length of formula using strlen:
$length_remaining = strlen($chemical_formula);

// create placeholder variable $i and an array to store each individual element;
$i = 0;
$array = array();

while ($length_remaining !=0) {
  //read $chemical_formula letter by letter into $array[$i] (use fgetc??) - Stop prior to reaching a capital letter, so for example $array[0] is assigned Na, $array[1] is N, and $array[2] is O3;
  //increase $i by 1 ($i++);
  //subtract the number of letters processed from the $length_remaining variable;
};

So at the end of this you'd be left with the $array of each of the individual elements. Hope that makes enough sense to use as a starting point!

Thanks! That is a good starting point. I will work on that. I am new to programming and I am seeing that creativity is essential. I will try to work on that today. I will seek to do it as you stated as well as to use matching to values in an array to fetch substring and store into variables. There is so many things I would like to write but I need to learn PHP better. My job gets in the way.

This worked! This also exposed me to something that seems to be very complicated called Perl Compatible Regular Expressions (PCRE). I am not sure if I am allowed to post links to other sites here that goes over this complicated information but it's out there. Anyway, Cheers!

<?php $str= "NaNO3";

$pieces = preg_split('/(?=[A-Z])/',$str);

var_dump($pieces);

?>

output as viewed in page source array(4) { [0]=> string(0) "" [1]=> string(2) "Na" [2]=> string(1) "N" [3]=> string(2) "O3" }