Sanitize and standardize a string that contains an indeterminate sequence of delimiting characters and whitespaces

I have a php variable that comes from a form that needs tidying up.

The variable contains a list of items (possibly two or three word items with a space in between words).

I want to convert it to a comma separated list with no superfluous white space. I want the divisions to fall only at commas, semi-colons or new-lines. Blank cannot be an item.

Here's a comprehensive example (with a deliberately messy input):

Input string:

$input = 'dog, cat         ,car,tea pot,,  ,,, ;;
fly,     cake';

Desired result string:

dog,cat,car,tea pot,fly,cake

Solution

You can start by splitting the string into "useful" parts, with preg_split, and, then, implode those parts back together :

$str_in = "dog, cat         ,car,tea pot,,  ,,, ;;
fly,     cake";

$parts = preg_split('/[,;\s]/', $str_in, -1, PREG_SPLIT_NO_EMPTY);

$str_out = implode(',', $parts);

var_dump($parts, $str_out);

(Here, the regex will split on ',', ';', and '\s', which means any whitespace character -- and we only keep non-empty parts)

Will get you, for $parts :

array
  0 => string 'dog' (length=3)
  1 => string 'cat' (length=3)
  2 => string 'car' (length=3)
  3 => string 'tea' (length=3)
  4 => string 'pot' (length=3)
  5 => string 'fly' (length=3)
  6 => string 'cake' (length=4)

And, for $str_out :

string 'dog,cat,car,tea,pot,fly,cake' (length=28)

Edit after the comment : sorry, I didn't notice that one ^^

In that case, you can't split by white-space :-( I would probably split by ',' or ';', iterate over the parts, using trim to remove white-characters at the beginning and end of each item, and only keep those that are not empty :

$useful_parts = array();
$parts = preg_split('/[,;]/', $str_in, -1, PREG_SPLIT_NO_EMPTY);
foreach ($parts as $part) {
    $part = trim($part);
    if (!empty($part)) {
        $useful_parts[] = $part;
    }
}
var_dump($useful_parts);

Executing this portion of code gets me :

array
  0 => string 'dog' (length=3)
  1 => string 'cat' (length=3)
  2 => string 'car' (length=3)
  3 => string 'tea pot' (length=7)
  4 => string 'fly' (length=3)
  5 => string 'cake' (length=4)

And imploding all together, I get, this time :

string 'dog,cat,car,tea pot,fly,cake' (length=28)

Which is better ;-)