How can I implode an array while skipping empty ar

问题:

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?

回答1:

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.

回答2:

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'));

回答3:

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"));
} 

回答4:

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 )

回答5:

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;
}

回答6:

Try this:

$result = array();

foreach($array as $row) { 
   if ($row != '') {
   array_push($result, $row); 
   }
}

implode('-', $result);

回答7:

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);

回答8:

Try this:

if(isset($array))  $array = implode(",", (array)$array);