Fatal error: [] operator not supported for string error on PHP Array in for loop

Question

I have this PHP Code:

for($i=1; $i<=$_POST[\"counter\"]; $i++)
{
    if($_POST[\"checkbox$i\"])
    {
        //select the billing_pdf row
        $sql=\"SELE         


        

Answer 1

You have already used $emails_list as a string some where in your page like $emails_list = 7;

and again using it like

$emails_list[] = array(1,2,4);