Perl's join() ignores (skips) empty array values; PHP's implode() does not appear to.
Suppose I have an array:
$array = array('one', '', '', 'four', '', 'six');
implode('-', $array);
yields:
one---four--six
instead of (IMHO the preferable):
one-four-six
Any other built-ins with the behaviour I'm looking for? Or is it going to be a custom jobbie?
You can use array_filter():
If no callback is supplied, all entries of input equal to
FALSE(see converting to boolean) will be removed.
implode('-', array_filter($array));
Obviously this will not work if you have 0 (or any other value that evaluates to false) in your array and you want to keep it. But then you can provide your own callback function.
false, and 0 are also thrown out?
empty, as you use it, will also treat 0 and false as false (and remove it) btw.
array_filter() by default filters off every false, null, empty string ('') and 0.false: empty array, 0.0 and "0".I suppose you can't consider it built in (because the function is running with a user defined function), but you could always use array_filter.
Something like:
function rempty ($var)
{
return !($var == "" || $var == null);
}
$string = implode('-',array_filter($array, 'rempty'));
empty has the same effect as passing no callback at all. Edit: You have to negate the return value. Otherwise only empty elements will be returned ;) (actually using empty as you did before was also wrong)
implode('-', array_filter($ary, create_function('$a', 'return $a!="";')));To remove null, false, empty string but preserve 0, etc. use func. 'strlen'
$arr = [null, false, "", 0, "0", "1", "2", "false"];
print_r(array_filter($arr, 'strlen'));
will output:
//Array ( [3] => 0 [4] => 0 [5] => 1 [6] => 2 [7] => false )
How you should implement you filter only depends on what you see as "empty".
function my_filter($item)
{
return !empty($item); // Will discard 0, 0.0, '0', '', NULL, array() of FALSE
// Or...
return !is_null($item); // Will only discard NULL
// or...
return $item != "" && $item !== NULL; // Discards empty strings and NULL
// or... whatever test you feel like doing
}
function my_join($array)
{
return implode('-',array_filter($array,"my_filter"));
}
$array = ["one", NULL, "two", NULL, "three"];
$string = implode("-", array_diff($array, [NULL]));
echo $string;
Returns one-two-three
Based on what I can find, I'd say chances are, there isn't really any way to use a PHP built in for that. But you could probably do something along the lines of this:
function implode_skip_empty($glue,$arr) {
$ret = "";
$len = sizeof($arr);
for($i=0;$i<$len;$i++) {
$val = $arr[$i];
if($val == "") {
continue;
} else {
$ret .= $arr.($i+1==$len)?"":$glue;
}
}
return $ret;
}
Try this:
$result = array();
foreach($array as $row) {
if ($row != '') {
array_push($result, $row);
}
}
implode('-', $result);
Not a direct answer, but just a general reminder that you don't have to rely on a separate named function —— you can do this with an inline anonymous function such as:
$imploded = implode("+", array_filter($array, function($chunk) {
return (trim($chunk)!="");
}));
array_fileter() seems to be the accepted way here, and is probably still the most robust answer tbh.
However, the following will also work if you can guarantee that the "glue" character doesn't already exist in the strings of each array element (which would be a given under most practical circumstances -- otherwise you wouldn't be able to distinguish the glue from the actual data in the array):
$array = array('one', '', '', 'four', '', 'six');
$str = implode('-', $array);
$str = preg_replace ('/(-)+/', '\1', $str);
Try this:
if(isset($array)) $array = implode(",", (array)$array);
isset() or casting the input array as array addresses any of the concerns of the original post?
joindoesn't skip undefined elements. In fact, they result in a warning.$a[0]="a"; $a[2]="c"; say join "-",@a;displaysUse of uninitialized value within @a in join or stringanda--c. One can usejoin '-', grep !defined, ...to skip undefined values.grep !length,will do empty strings.