How to explode only on the last occurring delimiter?

Question

$split_point = ' - ';
$string = 'this is my - string - and more';

How can I make a split using the second instance of $split_point and not the first one. Can I specify somehow a right to left search?

Basically how do I explode from right to left. I want to pick up only the last instance of " - ".

Result I need:

$item[0]='this is my - string';
$item[1]='and more';

and not:

$item[0]='this is my';
$item[1]='string - and more';

Answer 1

You may use strrev to reverse the string, and then reverse the results back:

$split_point = ' - ';
$string = 'this is my - string - and more';

$result = array_map('strrev', explode($split_point, strrev($string)));

Not sure if this is the best solution though.

Answer 2

How about this:

$parts = explode($split_point, $string);
$last = array_pop($parts);
$item = array(implode($split_point, $parts), $last);

Not going to win any golf awards, but it shows intent and works well, I think.

Answer 3

Here is another way of doing it:

$split_point = ' - ';
$string = 'this is my - string - and more';

$stringpos = strrpos($string, $split_point, -1);
$finalstr = substr($string,0,$stringpos);

Answer 4

If I understand correctly, you want the example case to give you ('this is my - string', 'and more')?

Built-in split/explode seems to be forwards-only - you'll probably have to implement it yourself with strrpos. (right-left search)

$idx = strrpos($string, $split_point);
$parts = array(substr($string, 0, $idx), substr($string, $idx+strlen($split_point)))

Answer 5

I am underwhelmed by all of the over-engineered answers which are calling many functions and/or iterating over data multiple times. All of those string and array reversing functions make the technique very hard to comprehend.

Regex is powerfully elegant in this case. This is exactly how I would do it in a professional application:

Code: (Demo)

$string = 'this is my - string - and more';
var_export(preg_split('~.*\K - ~', $string));

Output:

array (
  0 => 'this is my - string',
  1 => 'and more',
)

By greedily matching characters (.*), then restarting the fullstring match (\K), then matching the last occurring delimiting substring (" - "), you are assured to only separate the final substring from the string.

Answer 6

Why not split on ' - ', but then join the first two array entries that you get back together?

Answer 7

I liked Moff's answer, but I improved it by limiting the number of elements to 2 and re-reversing the array:

$split_point = ' - ';
$string = 'this is my - string - and more';

$result = array_reverse(array_map('strrev', explode($split_point, strrev($string),2)));

Then $result will be :

Array ( [0] => this is my - string [1] => and more )

Answer 8

this is my - string - and more

1. Use common explode function to get all strings
2. Get sizeof array and fetch last item
3. Pop last item using array_pop function.
4. Implode remaining string with same delimeter(if u want other delimeter can use).

Code

$arrSpits=explode("", "this is my - string - and more");
$arrSize=count($arrSpits);

echo "Last string".$arrSpits[arrSize-1];//Output: and more


array_pop(arrSpits); //now pop the last element from array

$firstString=implode("-", arrSpits);
echo "First String".firstString; //Output: this is my - string

Answer 9

I've stumbled uppon the same, and fixed it like so:

$split_point = ' - ';
$string = 'this is my - string - and more';

$reverse_explode = array_reverse(explode($split_point, $string));

Answer 10

Just an idea:

function explode_reversed($delim,$s){
  $result = array();
  $w = "";
  $l = 0;
  for ($i = strlen($s)-1; $i>=0; $i-- ):
    if ( $s[$i] == "$delim" ):
      $l++;
      $w = "";
    else:
      $w = $s[$i].$w;
    endif;
    $result[$l] = $w;
  endfor;
return $result;
}
$arr = explode_reversed(" ","Hello! My name is John.");
print_r($arr);

Result:

Array
(
    [0] => John.
    [1] => is
    [2] => name
    [3] => My
    [4] => Hello!
)

But this is much slower then explode. A test made:

$start_time = microtime(true);
for ($i=0; $i<1000;$i++)   
  $arr = explode_reversed(" ","Hello! My name is John.");
$time_elapsed_secs = microtime(true) - $start_time;
echo "time: $time_elapsed_secs s<br>";

Takes 0.0625 - 0.078125s

But

for ($i=0; $i<1000;$i++)   
  $arr = explode(" ","Hello! My name is John.");

Takes just 0.015625s

The fastest solution seems to be:

array_reverse(explode($your_delimiter, $your_string));

In a loop of 1000 times this is the best time I can get 0.03125s.

Answer 11

Not sure why no one posted a working function with $limit support though here it is for those who know that they'll be using this frequently:

<?php
function explode_right($boundary, $string, $limit)
{
 return array_reverse(array_map('strrev', explode(strrev($boundary), strrev($string), $limit)));
}

$string = 'apple1orange1banana1cupuacu1cherimoya1mangosteen1durian';
echo $string.'<br /><pre>'.print_r(explode_right(1, $string, 3),1).'</pre>';
?>

Answer 12

Assuming you only want the first occurrence of $split_point to be ignored, this should work for you:

# retrieve first $split_point position
$first = strpos($string, $split_point);
# retrieve second $split_point positon
$second = strpos($string, $split_point, $first+strlen($split_point));
# extract from the second $split_point onwards (with $split_point)
$substr = substr($string, $second);

# explode $substr, first element should be empty
$array = explode($split_point, $substr);

# set first element as beginning of string to the second $split_point
$array[0] = substr_replace($string, '', strpos($string, $substr));

This will allow you to split on every occurrence of $split_point after (and including) the second occurrence of $split_point.

Answer 13

$split_point = ' - ';
$string = 'this is my - string - and more';
$result = end(explode($split_point, $string));

This is working fine