How to pass array parameters in url - PHP - php

Question

I'm tryng to pass parameters in the url, but I receive this error:
*implode(): Invalid arguments passed in *
I know that the cause is that I pass a string as parameter instead of an array, but how can I do to pass the array directly?
My code:
$all_prod_cat="SELECT * FROM products GROUP BY product_category";
$run_all_prod_cat = mysqli_query($con,$all_prod_cat);
$sql= "SELECT * FROM products";
if(isset($_GET['product_category']) && $_GET['product_category']!="")
{
$risperpag = 16;
$limit = $risperpag * $_GET['p'] - $risperpag;
$prod_cat = $_GET['product_category'];
$sql.=",categories WHERE product_category IN ('".implode("','",$prod_cat)."') AND product_category = cat_id LIMIT $limit,$risperpag";
$get_cat_pro_total = "SELECT * FROM products,categories WHERE product_category IN ('".implode("','",$prod_cat)."') AND product_category = cat_id";
$run_cat_pro_total = mysqli_query($con,$get_cat_pro_total);
$num_cat_pro_total = mysqli_num_rows($run_cat_pro_total);
$npag = ceil($num_cat_pro_total / $risperpag);
$p = $_GET['p'];
echo "<ul>";
if($p!=1)
{
echo '<li class="numPagine">← Indietro</li>';
}
for($i=1;$i<=$npag;$i++){
if($p==$i)
{
echo '<li class="numPagine pagina_attuale">'.$i.'</li>';
}
else
{
echo '<li class="numPagine">'.$i.'</li>';
}
}
if($p!=$npag)
{
echo '<li class="numPagine">Avanti →</li>';
}
echo "</ul>";
}
The problem is when I set the urlencode parameter, I tried to serialize, but I get an other error. I think I should unserialize, but I don't know the exact point.
Thanks in advance.

Answer 1

It is possible to generate url with get params using http_build_query function.
$urlparams = [
'product_category' => [
'cat1',
'cat2',
'cat3',
'cat4'
]
];
echo http_build_query($urlparams);