PHP Notice: Undefined index - Contact Form not working [duplicate] - php

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This question already has answers here:
"Notice: Undefined variable", "Notice: Undefined index", "Warning: Undefined array key", and "Notice: Undefined offset" using PHP
(29 answers)
Closed 6 years ago.
so this is a Contact Form php script with basic validations. This script was running absolutely fine without any issues or errors. Until recently I transferred the file to another web hosting.
The previous web host had PHP version 5.4.35
While the new web host has PHP version 5.4.45
I don't know much about PHP so I don't know what's going on. Here's what the error_log had logged everytime someone submitted the contact form.
[17-Jun-2016 17:05:20 Etc/GMT] PHP Notice: Undefined index: name in /home/domain/public_html/contact.php on line 70
[17-Jun-2016 17:05:20 Etc/GMT] PHP Notice: Undefined index: email in /home/domain/public_html/contact.php on line 76
[17-Jun-2016 17:05:20 Etc/GMT] PHP Notice: Undefined index: message in /home/domain/public_html/contact.php on line 82
In order to solve this I initialized the error variables ($name,$email,$message) as null in that case there was no more errors but the contact form failed to work.
Please help me! I don't know why this problem is occuring.
<?php
if (isset($_POST["submit"])) {
$name = $_POST['name'];
$email = $_POST['email'];
$message = $_POST['message'];
$human = intval($_POST['human']);
$to = 'example#domain.com';
$subject = 'Contact Form';
$header = "From:contact#domain.com \r\n";
$header = "Cc:contact2#domain.com \r\n";
$header .= "MIME-Version: 1.0\r\n";
$header .= "Content-type: text/html\r\n";
$body = "From: $name\n E-Mail: $email\n Message:\n $message";
if (!$_POST['name']) {
$errName = 'Please enter your name';
}
if (!$_POST['email'] || !filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
$errEmail = 'Please enter a valid email address';
}
if (!$_POST['message']) {
$errMessage = 'Please enter your message';
}
if ($human !== 2) {
$errHuman = 'Your anti-spam is incorrect';
}
if (!$errName && !$errEmail && !$errMessage && !$errHuman) {
if (mail($to, $subject, $body, $header)) {
$result='Thank You! Your message will be replied soon!';
} else {
$result='Sorry there was an error sending your message.';
}
}
}
?>
<form class="col l12" method="post" action="contact.php">
<input id="name" name="name" type="text" class="validate" value="<?php echo htmlspecialchars($_POST['name']); ?>">
<?php echo "<p class='red-text'>$errName</p>";?>
<label for="name">Name</label>
<input id="email" name="email" type="email" class="validate" value="<?php echo htmlspecialchars($_POST['email']); ?>">
<?php echo "<p class='red-text'>$errEmail</p>";?>
<label for="email">Email</label>
<textarea name="message" class="materialize-textarea"><?php echo htmlspecialchars($_POST['message']);?></textarea>
<?php echo "<p class='red-text'>$errMessage</p>";?>
<label for="message">Message</label>
<label for="human"><strong>AntiSPAM Check:</strong> 5 - 3 = ?</label>
<input id="human" name="human" type="text" class="validate">
<?php echo "<p class='red-text'>$errHuman</p>";?>
<p class="left-align"><button class="blue darken-1 btn-large waves-effect waves-light" id="submit" type="submit" style="font-weight:500;" name="submit">Send</button>
<?php echo $result; ?>
</form>

Answer 1

Those errors are telling you that your $_POST array doesn't have name or email or message. Someone submitted an empty form.
Now, you check for missing values later on in your script, but not until after you've already tried to access these missing array values.
Best thing would be to move your validation code...
if (!$_POST['name']) {
...
...to the top so it runs first. Then, only do $name = $_POST['name']; once you're sure that it exists.