How to implode array with key and value without foreach in PHP

You could use http_build_query, like this:

<?php
  $a=array("item1"=>"object1", "item2"=>"object2");
  echo http_build_query($a,'',', ');
?>

Output:

item1=object1, item2=object2 

Demo

I spent measurements (100000 iterations), what fastest way to glue an associative array?

Objective: To obtain a line of 1,000 items, in this format: "key:value,key2:value2"

We have array (for example):

$array = [
    'test0' => 344,
    'test1' => 235,
    'test2' => 876,
    ...
];

Test number one:

Use http_build_query and str_replace:

str_replace('=', ':', http_build_query($array, null, ','));

Average time to implode 1000 elements: 0.00012930955084904

Test number two:

Use array_map and implode:

implode(',', array_map(
        function ($v, $k) {
            return $k.':'.$v;
        },
        $array,
        array_keys($array)
    ));

Average time to implode 1000 elements: 0.0004890081976675

Test number three:

Use array_walk and implode:

array_walk($array,
        function (&$v, $k) {
            $v = $k.':'.$v;
        }
    );
implode(',', $array);

Average time to implode 1000 elements: 0.0003874126245348

Test number four:

Use foreach:

    $str = '';
    foreach($array as $key=>$item) {
        $str .= $key.':'.$item.',';
    }
    rtrim($str, ',');

Average time to implode 1000 elements: 0.00026632803902445

I can conclude that the best way to glue the array - use http_build_query and str_replace

and another way:

$input = array(
    'item1'  => 'object1',
    'item2'  => 'object2',
    'item-n' => 'object-n'
);

$output = implode(', ', array_map(
    function ($v, $k) {
        if(is_array($v)){
            return $k.'[]='.implode('&'.$k.'[]=', $v);
        }else{
            return $k.'='.$v;
        }
    }, 
    $input, 
    array_keys($input)
));

or:

$output = implode(', ', array_map(
    function ($v, $k) { return sprintf("%s='%s'", $k, $v); },
    $input,
    array_keys($input)
));

I would use serialize() or json_encode().

While it won't give your the exact result string you want, it would be much easier to encode/store/retrieve/decode later on.