php explode every third instance of character

Question

How can I explode every third semicolon (;) as a piece?

example data: $string = piece1;piece2;piece3;piece4;piece5;piece6;piece7;piece8;

example output would be:

$output[0] = piece1;piece2:piece3;

$output[1] = piece4;piece5;piece6;

$output[2] = piece7;piece8;

Thanks!

Answer 1

I am sure you can do something slick with regular expressions, but why not just explode the each semicolor and then add them three at a time.

$tmp = explode(";", $string);
$i=0;
$j=0;

foreach($tmp as $piece) {
   if(! ($i++ %3)) $j++;   //increment every 3 
   $result[$j] .= $piece;
}

Answer 2

Maybe approach it from a different angle. Explode() it all, then combine it back in triples. Like so...

$str = "1;2;3;4;5;6;7;8;9";
$boobies = explode(";", $array);
while (!empty($boobies))
{
  $foo = array();
  $foo[] = array_shift($boobies);
  $foo[] = array_shift($boobies);
  $foo[] = array_shift($boobies);
  $bar[] = implode(";", $foo) . ";";
}

print_r($bar);

Array ( [0] => 1;2;3; [1] => 4;5;6; [2] => 7;8;9; )

Answer 3

$string = "piece1;piece2;piece3;piece4;piece5;piece6;piece7;piece8;piece9;";
preg_match_all('/([A-Za-z0-9\.]*;[A-Za-z0-9\.]*;[A-Za-z0-9\.]*;)/',$string,$matches);

print_r($matches);

Array
(
    [0] => Array
        (
            [0] => piece1;piece2;piece3;
            [1] => piece4;piece5;piece6;
            [2] => piece7;piece8;piece9;
        )

    [1] => Array
        (
            [0] => piece1;piece2;piece3;
            [1] => piece4;piece5;piece6;
            [2] => piece7;piece8;piece9;
        )

)

Answer 4

Here's a regex approach, which I can't say is all too good looking.

$str='';
for ($i=1; $i<20; $i++) {
    $str .= "$i;";
}

$split = preg_split('/((?:[^;]*;){3})/', $str, -1,
                    PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);

Output:

Array
(
    [0] => 1;2;3;
    [1] => 4;5;6;
    [2] => 7;8;9;
    [3] => 10;11;12;
    [4] => 13;14;15;
    [5] => 16;17;18;
    [6] => 19;
)

Answer 5

Another regex approach.

<?php
$string = 'piece1;piece2;piece3;piece4;piece5;piece6;piece7;piece8';
preg_match_all('/([^;]+;?){1,3}/', $string, $m, PREG_SET_ORDER);
print_r($m);

Results:

Array
(
    [0] => Array
        (
            [0] => piece1;piece2;piece3;
            [1] => piece3;
        )

    [1] => Array
        (
            [0] => piece4;piece5;piece6;
            [1] => piece6;
        )

    [2] => Array
        (
            [0] => piece7;piece8
            [1] => piece8
        )

)

Answer 6

Regex Split

$test = ";2;3;4;5;6;7;8;9;10;;12;;14;15;16;17;18;19;20";
// match all groups that:
// (?<=^|;) follow the beginning of the string or a ;
// [^;]*  have zero or more non ; characters
// ;? maybe a semi-colon (so we catch a single group)
// [^;]*;? again (catch second item)
// [^;]* without the trailing ; (to not capture the final ;)
preg_match_all("/(?<=^|;)[^;]*;?[^;]*;?[^;]*/", $test, $matches);
var_dump($matches[0]);


array(7) {
  [0]=>
  string(4) ";2;3"
  [1]=>
  string(5) "4;5;6"
  [2]=>
  string(5) "7;8;9"
  [3]=>
  string(6) "10;;12"
  [4]=>
  string(6) ";14;15"
  [5]=>
  string(8) "16;17;18"
  [6]=>
  string(5) "19;20"
}

Answer 7

Essentially the same solution as the other ones that explode and join again...

$tmp = explode(";", $string);

while ($tmp) {
    $output[] = implode(';', array_splice($tmp, 0, 3));
};

Answer 8

Easiest solution I can think of is:

$chunks = array_chunk(explode(';', $input), 3);
$output = array_map(create_function('$a', 'return implode(";",$a);'), $chunks);