Fastest way to implode an associative array with keys

I'm looking for a fast way to turn an associative array in to a string. Typical structure would be like a URL query string but with customizable separators so I can use '&' for xhtml links or '&' otherwise.

My first inclination is to use foreach but since my method could be called many times in one request I fear it might be too slow.

<?php
$Amp = $IsXhtml ? '&amp;' : '&';
$Parameters = array('Action' => 'ShowList', 'Page' => '2');
$QueryString = '';
foreach ($Parameters as $Key => $Value)
        $QueryString .= $Amp . $Key . '=' . $Value;

Is there a faster way?

You can use http_build_query() to do that.

> Generates a URL-encoded query string from the associative (or indexed) array provided.

If you're not concerned about the exact formatting however you do want something simple but without the line breaks of print_r you can also use json_encode($value) for a quick and simple formatted output. (note it works well on other data types too)

$str = json_encode($arr);
//output...
[{"id":"123","name":"Ice"},{"id":"234","name":"Cake"},{"id":"345","name":"Pie"}]

As an aside, I was in search to find the best way to implode an associative array but using my own seperators etc...

So I did this using PHP's array_walk() function to let me join an associative array into a list of parameters that could then be applied to a HTML tag....

// Create Params Array
$p = Array("id"=>"blar","class"=>"myclass","onclick"=>"myJavascriptFunc()");

// Join Params
array_walk($p, create_function('&$i,$k','$i=" $k=\"$i\"";'));
$p_string = implode($p,"");

// Now use $p_string for your html tag

Obviously, you could stick that in your own function somehow but it gives you an idea of how you can join an associative array using your own method. Hope that helps someone :)

One way is using print_r(array, true) and it will return string representation of array

This is my solution for example for an div data-attributes:

<?

$attributes = array(
    'data-href'   => 'http://example.com',
    'data-width'  => '300',
    'data-height' => '250',
    'data-type'   => 'cover',
);

$dataAttributes = array_map(function($value, $key) {
    return $key.'="'.$value.'"';
}, array_values($attributes), array_keys($attributes));

$dataAttributes = implode(' ', $dataAttributes);

?>

<div class="image-box" <?= $dataAttributes; ?> >
    <img src="http://example.com/images/best-of.jpg" alt="">
</div>

My solution:

$url_string = http_build_query($your_arr);
$res = urldecode($url_string); 

What about this shorter, more transparent, yet more intuitive with array_walk

$attributes = array(
  'data-href'   => 'http://example.com',
  'data-width'  => '300',
  'data-height' => '250',
  'data-type'   => 'cover',
);

$args = "";
array_walk(
	$attributes, 
	function ($item, $key) use (&$args) {
		$args .= $key ." = '" . $item . "' ";  
	}
);
// output: 'data-href="http://example.com" data-width="300" data-height="250" data-type="cover"

A one-liner for creating string of HTML attributes (with quotes) from a simple array:

$attrString = str_replace("+", " ", str_replace("&", "\" ", str_replace("=", "=\"", http_build_query($attrArray)))) . "\"";

Example:

$attrArray = array("id"    => "email", 
                   "name"  => "email",
                   "type"  => "email",
                   "class" => "active large");

echo str_replace("+", " ", str_replace("&", "\" ", str_replace("=", "=\"", http_build_query($attrArray)))) . "\"";

// Output:
// id="email" name="email" type="email" class="active large"

function array_to_attributes ( $array_attributes )
{

	$attributes_str = NULL;
	foreach ( $array_attributes as $attribute => $value )
	{

		$attributes_str .= " $attribute=\"$value\" ";

	}

	return $attributes_str;
}

$attributes = array(
    'data-href'   => 'http://example.com',
    'data-width'  => '300',
    'data-height' => '250',
    'data-type'   => 'cover',
);

echo array_to_attributes($attributes) ;

Use array_walk for this.

$arr = [
    "key"  => "value",
    "key2" => "value2",
];

array_walk($arr, function(&$value, $key) {
    $value = "{$key}: {$value}";
});

implode("<br/>", $arr)

Result

key: value<br/>key2: value2<br/>

This is the most basic version I can think of:

public function implode_key($glue = "", $pieces = array())
{
    $keys = array_keys($pieces);
    return implode($glue, $keys);
}

echo implode(",", array_keys($companies->toArray()));

$companies->toArray() -- this is just in case if your $variable is an object, otherwise just pass $companies.

That's it!