Q:

Php Undefine Index Issue

I'm creating a contact form with php. But when i run it in my xampp server  i get a error message. I don't understand why this happened. I can't figure it out. Following is my error message.
Error Message:
Notice: Undefined index: Send in D:\Software\Installed\xampp\htdocs\Omdatech-Co\eng\resellers.php on line 91 (First Line ex: if(isset($_POST['Send']) & $_POST['Send'] == "Submit")) 

Php code:
<?php
        if(isset($_POST['Send']) & $_POST['Send'] == "Submit")
        {
            $fname = mysql_real_escape_string($_POST['fname']);
            $email = mysql_real_escape_string($_POST['email']);
            $conum = mysql_real_escape_string($_POST['conum']);
            $country = mysql_real_escape_string($_POST['country']);
            $find = mysql_real_escape_string($_POST['find']);
            $msg = mysql_real_escape_string($_POST['msg']);

            $err = array();

if(isset($fname) & isset($email) & isset($conum) & isset($country) & isset($find) & 
isset($msg))
            {
if(empty($fname) & empty($email) & empty($conum) & empty($country) & empty($find) & 
empty($msg))
                {
                    $err[] = "All field require";
                }
                else
                {
                    if(empty($fname))
                    $err[] = "Your first name require";
                }

            }
            else
            {
            if(!empty($err))
                            {
                                foreach($err as $er)
                                {
                                    echo "<font color=red>$er</font><br/>";
                                }
                            }
                            else
                            {
                                echo "Thank you.";
                            }
            }

        }           
        ?>

Can anyone fix that issue? Why i get this message ? 

A:

Because you're using the bitwise operator when you need the logical operator:
if(isset($_POST['Send']) && $_POST['Send'] == "Submit")

Note the two && and not &.
The logical operators short-circuit, so when isset() returns false, the following comparison isn't evaluated. The bitwise operator attempts to compute a value, and evaluates the comparison, hence the warning.

