How to join array values in PHP

Question

I have a PHP array:

array
  0 => 
    array
      'cid' => string '18427' (length=5)
  1 => 
    array
      'cid' => string '17004' (length=5)
  2 => 
    array
      'cid' => string '19331' (length=5)

I want to join the values so I can get a string like this:

18427,17004,19331

I tried the implode PHP function, But I get an error:

A PHP Error was encountered

How can join only the values which are in cid?

Answer 1

You have to map the array values first:

echo join(',', array_map(function($item) {
    return $item['cid'];
}, $arr));

Without closures it would look like this:

function get_cid($item)
{
  return $item['cid'];
}

echo join(',', array_map('get_cid', $arr));

See also: array_map()