Q:

How to merge Multiple arrays into single array using PHP

i query the address column from the database and i pass that multiple address to the Google Geocoder API and i store that latitude and longitude result in the $coordinate variable. When i var_export($coordinate); i get the output in the below format:
'[19.0759837,72.8776559]''[47.6062095,-122.3320708]''[12.9715987,77.5945627]'

but in when use print_r(array($variablename)); i get the output in this format:
Array
(
 [0] => [19.0759837,72.8776559]
)
Array
(
  [0] => [47.6062095,-122.3320708]
)
Array
(
  [0] => [12.9715987,77.5945627]
)

But i want the output to be in single array something like this.
Array
(
 [0] => [19.0759837,72.8776559],
 [1] => [47.6062095,-122.3320708],
 [2] => [12.9715987,77.5945627]
)

This is php code:
<?php 
    // database connection code and query to fetch address column the database and pass address to geocode()
header("content-type: application/json");
        header('Access-Control-Allow-Origin: *');
        $config = parse_ini_file('./config.ini');
        $connect = mysqli_connect('localhost',$config['username'],$config['password'],$config['dbname']);
        if (mysqli_connect_errno())
                {
                  echo "Failed to connect to MySQL: " . mysqli_connect_error();
                }
                $ordertracker = mysqli_query($connect, "select address from ordertracker");

                if (!$ordertracker)
                {
                    echo "Error fetching results: " . mysqli_error();

                }

        $address=array();
        while($row = mysqli_fetch_assoc($ordertracker)) {
             $address= $row['address'];
              geocode($address);  
        }
    function geocode($address)
     {
                $address = urlencode($address);
                $url = "http://maps.googleapis.com/maps/api/geocode/json?address=$address&sensor=false";
                $geocode=file_get_contents($url);
                $output= json_decode($geocode);
                $lat = $output->results[0]->geometry->location->lat;
                $long = $output->results[0]->geometry->location->lng;
                $coordinate = "[" . $lat . "," . $long . "]";  
                var_export($coordinate);  
      }
    ?>

A:

If you want an array, then you should not use string literals and concatenation to build it, as that will result in a string.
Instead let your function result an array with two values (latitude and longitude) and append those pairs to your main array in your main loop:
$address = [];
while($row = mysqli_fetch_assoc($ordertracker)) {
    $address[] = geocode($row['address']);
}
print_r($address);

function geocode($address) {
    $address = urlencode($address);
    $url = "http://maps.googleapis.com/maps/api/geocode/json?address=$address&sensor=false";
    $geocode = file_get_contents($url);
    $output= json_decode($geocode);
    $lat = $output->results[0]->geometry->location->lat;
    $long = $output->results[0]->geometry->location->lng;
    $coordinate = [$lat, $long];  
    return $coordinate;
}

