PHP form , showing message after submission - php

Question

I am making a PHP form and not sure how to go about having the code say "message delivered" when clicking submission and having it validate correctly. Here is my code so far. I realize that the message appears anytime you click submit. Thank you for your patience.
<?php
// define variables and set to empty values
$nameErr = $emailErr = $genderErr = $websiteErr = "";
$name = $email = $comment = $message = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if (empty($_POST["name"])) {
$nameErr = "Name is required";
} else {
$name = test_input($_POST["name"]);
}
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["comment"])) {
$comment = "";
} else {
$comment = test_input($_POST["comment"]);
}
if (isset($_POST["submit"])) {
$message = "Message has been delivered";
}
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
?>
<div class="cntr">
<h2>Contact Form</h2>
<p><span class="error">* required field.</span></p>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
<div class="field">
<label for="name">Name </label>
<br>
<input type="text" name="name">
<span class="error">*<?php echo $nameErr;?></span>
</div>
<div class="field">
<label for="email">Email</label>
<br>
<input type="text" name="email">
<span class="error">* <?php echo $emailErr;?></span>
</div>
<div class="field">
<label for="message">Message</label>
<br>
<textarea name="comment" rows="8" cols="40"></textarea>
</div>
<button type="submit" class="email" name="submit" value="Submit">Submit</button>
<?php echo $message; ?><br/>
</form>
</div>

Answer 1

Use
if (isset($_POST["submit"]) && empty($nameErr) && empty($genderErr) && empty($emailErr) && empty($websiteErr)) {
$message = "Message has been delivered";
}
instead of
if (isset($_POST["submit"])) {
$message = "Message has been delivered";
}
Because isset($_POST["submit"]) is true when ever you do a submit , so you need to check the error variables are empty also . if the error variables are empty that means your code validated and passed .