Redirecting to success page after validation - php

Question

I thought of using php header to redirect upon validation successful. However it's seems broken to me. How do I implement one then. Condition is when all the validation is validated then it would only redirect.
<?php
// define variables and set to empty values
$nameErr = $lastnameErr = $emailErr = $passwordErr = $confirmpasswordErr = $checkboxErr= "";
$name = $lastname = $email = $password = $confirmpassword = $checkbox = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if (empty($_POST["firstname"])) {
$nameErr = "First Name is required";
}else {
$name = test_input($_POST["firstname"]);
}
if (empty($_POST["lastname"])) {
$lastnameErr = "Last Name is required";
}else {
$name = test_input($_POST["lastname"]);
}
if (empty($_POST["email"])) {
$emailErr = "Email is required";
}else {
$email = test_input($_POST["email"]);
// check if e-mail address is well-formed
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid email format";
}
}
if(!empty($_POST["password"]) && ($_POST["password"] == $_POST["confirmpassword"])) {
$password = test_input($_POST["password"]);
$confirmpassword = test_input($_POST["confirmpassword"]);
if (strlen($_POST["password"]) <= '8') {
$passwordErr = "Your Password Must Contain At Least 8 Characters!";
}
elseif(!preg_match("#[0-9]+#",$password)) {
$passwordErr = "Your Password Must Contain At Least 1 Number!";
}
elseif(!preg_match("#[A-Z]+#",$password)) {
$passwordErr = "Your Password Must Contain At Least 1 Capital Letter!";
}
elseif(!preg_match("#[a-z]+#",$password)) {
$passwordErr = "Your Password Must Contain At Least 1 Lowercase Letter!";
}
}
elseif(empty($_POST["password"])) {
$passwordErr = "Password not filled at all";
}
elseif(!empty($_POST["password"])) {
$confirmpasswordErr = "Password do not match";
}
if(!isset($_POST['checkbox'])){
$checkboxErr = "Please check the checkbox";
}
else {
$checkbox = test_input($_POST["checkbox"]);
}
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
?>
header('Location: http://www.example.com/');

Answer 1

Set $error = 1 if any condition get failed , and at the bottom check if($error!=1) then redirect
and you can also use javascript redirect if header is not working

Answer 2

Look at the closing "?>"-Tab. header will generate a html-header, but is a php-function and should be inside the ?php ?> bracket.
Consider using html5 input validation - saves some code and server roundtrips to let the browser do the validation
Omit the closing "?>" altogether. Its not necessary and can lead to hard to see errors when there is content - even blanks - after the "?>"
Consider using the filter_input function with appropriate parameters to access $_POST and set your variables.