Explode string on commas and trim potential spaces from each value

Question

For example, I would like to create an array from the elements in this string:

$str = 'red,     green,     blue ,orange';

I know you can explode and loop through them and trim:

$arr = explode(',', $str);
foreach ($arr as $value) {
    $new_arr[] = trim($value);
}

But I feel like there's a one line approach that can handle this. Any ideas?

Jere

Answer 1

You can do the following using array_map:

$new_arr = array_map('trim', explode(',', $str));

Jere

This is also looping (internally) by PHP – Gormandize

@JasonOOO I think in most people's opinion, a couple milliseconds (if even that) is a fair tradeoff for having a line of code that is short, simple and easily readable. – Meador

Simple and easy to understand. However, if dealing with large data sets, the more performant answer provided by @amr-eladwy is the better solution. – Compression

Answer 2

An improved answer

preg_split ('/(\s*,*\s*)*,+(\s*,*\s*)*/', 'red,     green thing ,,
              ,,   blue ,orange');

Result:

Array
(
    [0] => red
    [1] => green thing
    [2] => blue
    [3] => orange
)

This:

• Splits on commas only
• Trims white spaces from each item.
• Ignores empty items
• Does not split an item with internal spaces like "green thing"

Gogetter

Can anyone explain me why this answer does not have 100 upvotes? Regexp is hard to understand, but it parsed my 100Mb file faster than other solutions – Pasquinade

Sorry but this regex is wrong - try replacing red with *red*. A better one might be /(\s*,\s*)+/ – Amalita

@AmrElAdawy FYI this no longer works after the 8/28 update. With the regex in the answer as-is, white space is not trimmed from some of the elements. Ex: ` green thing`. – Ruggles

Hi @Ruggles , can you help me more about that update? Do you have fiddler I can play around with? – Gogetter

@AmrElAdawy here you go: phpliveregex.com/p/rrI#tab-preg-split – Ruggles

@Ruggles updated. Please let me know if you see any issue. – Gogetter

Why your regexp not trim spaces around string? Example: ' red, green thing ,, ,, blue ,orange ' – Predecease

Answer 3

The following also takes care of white-spaces at start/end of the input string:

$new_arr = preg_split('/\s*,\s*/', trim($str));

and this is a minimal test with white-spaces in every sensible position:

$str = ' first , second , third , fourth, fifth ';
$new_arr = preg_split('/\s*,\s*/', trim($str));
var_export($str);

Ricks

Since array_map and regexp solutions produce identical results, could anyone compare their performance? – Pasquinade

@Pasquinade For cases like this, it will not be any difference. – Mesmerism

Answer 4

this how you replace and explode in a single line of code

$str = 'red,     green,     blue ,orange';

$new_string = explode(',',preg_replace('/\s+/', '', $str));

will output the results as

Array
(
    [0] => red
    [1] => green
    [2] => blue
    [3] => orange
)

Branching

this removes space within string. eg., 'navy blue' becomes 'naviblue' – Labionasal

Answer 5

By combining some of the principals in the existing answers I came up with

preg_split ('/\s*,+\s*/', 'red,     green thing ,,  ,,   blue ,orange', NULL, PREG_SPLIT_NO_EMPTY);

The reasoning behind it is that I found a bug in this answer, where if there is a comma at the end of the string it'll return a blank element in the array. i.e.

preg_split ('/(\s*,*\s*)*,+(\s*,*\s*)*/', 'red,     green thing ,,  ,,   blue ,orange,');

Results in

Array
(
  [0] => red
  [1] => green thing
  [2] => blue
  [3] => orange
  [4] => ''
)

You can fix this by using PREG_SPLIT_NO_EMPTY as mentioned in this answer to remove it, but once you are doing that there is technically no need to remove consecutive commas via the regex, thus the shortened expression

Antichlor

Answer 6

You can also do this with a one line regex

preg_split('@(?:\s*,\s*|^\s*|\s*$)@', $str, NULL, PREG_SPLIT_NO_EMPTY);

Kamacite

it creates multiple matches for spaces before and after in a string, for example " one, two, three " generates: Array ( [0] => [1] => one [2] => two [3] => three [4] => [5] => ) – Cavity

Answer 7

try this:

$str = preg_replace("/\s*,\s*/", ",", 'red,     green,     blue ,orange');

Gormandize

The OP wants an array. preg_replace() doesn't generate an array from a string. This is the right answer to the wrong question. Downvoted. – Jedlicka

$list = preg_split("/\s*,\s*/", 'red, green, blue ,orange'); minor modification rehabilitates the answer – Imaginary

Answer 8

SPECIFICALLY for the OP's sample string, because each substring to be matched is a single word, you can use str_word_count().

Code: (Demo)

$str = ' red,     green,     blue ,orange ';
var_export(str_word_count($str,1));  // 1 means return all words in an indexed array

Output:

array (
  0 => 'red',
  1 => 'green',
  2 => 'blue',
  3 => 'orange',
)

This can also be adapted for substrings beyond letters (and some hyphens and apostrophes -- if you read the fine print) by adding the necessary characters to the character mask / 3rd parameter.

Code: (Demo)

$str = " , Number1 ,     234,     0 ,4heaven's-sake  ,  ";
var_export(str_word_count($str,1,'0..9'));

Output:

array (
  0 => 'Number1',
  1 => '234',
  2 => '0',
  3 => '4heaven\'s-sake',
)

---

Again, I am treating this question very narrowly because of the sample string, but this will provide the same desired output:

Code: (Demo)

$str = ' red,     green,     blue ,orange ';
var_export(preg_match_all('/[^, ]+/',$str,$out)?$out[0]:'fail');

---

Finally, if you want to split on commas with optional leading or trailing spaces, here is the call: (Demo)

var_export(
    preg_split ('/ *,+ */', $str, 0, PREG_SPLIT_NO_EMPTY)
);

Jedlicka

Answer 9

You can use preg_split() for that.

$bar = preg_split ('/[,\s]+/', $str);
print_r ($bar);

/* Result:
  Array
  (
      [0] => red
      [1] => green
      [2] => blue
      [3] => orange
  )
 */

Apiculture

That will split on spaces in your elements – Reo

Move the comma to left of square braces to make the comma required. – Burkley

Moving the comma to the left won't solve that. Please check my answer below https://mcmap.net/q/118034/-explode-string-on-commas-and-trim-potential-spaces-from-each-value – Gogetter

Answer 10

$str = str_replace(" ","", $str);

Josephina

Trim does more than this... It trims \t\n\r\0\x0B also – Scenarist

Not only that, but this will screw up elements with space. – Disapproval

Answer 11

trim and explode

$str = 'red, green, blue ,orange';

$str = trim($str);

$strArray = explode(',',$str);

print_r($strArray);

Marti

This only strips whitespace from the beginning and end of a string, not between each colour. – Jere