Form validation without losing Form data - php

Question

I've set up a form with validation in PHP which works fine. The issue I'm facing is that validation occurs once the submit button is clicked. The form values get erased when the submit button is clicked. If there is a validation error, the user needs to fill all the values again instead of just the error one. Is there a way that once submit button is clicked the form values don't get erased?
<tr>
<td><label for="email_address">Email Address:</label> <input type="text" name="email_address" id="email_address" required /></td>
</tr>
<tr>
<td><label for="password">Password:</label> <input type="password" size="25" maxlength="25" name="password" id="password" required /></td>
</tr>
<tr>
<td><label for="password2">Re-enter Password:</label> <input type="password" size="25" maxlength="25" name="password2" id="password2" required /></td>
</tr>
<tr>
<td><input type="submit" name="submit" value="Submit" /></td>
</tr>
<tr>
<?php
if(isset($_POST['submit'])){
$email_address = $_POST['email_address'];
$password = $_POST['password'];
$password2 = $_POST['password2'];
if (!preg_match("/([\w\-]+\#[\w\-]+\.[\w\-]+)/",$email_address)) {
?>
<td><?php echo "Enter Valid Email Address"; ?></td>
<?php
}
elseif ($password2 !== $password) {
?>
<td><?php echo "Passwords don't match"; ?></td>
<?php
}

Answer 1

You need to echo out the user-entry into the value of the input tags. These kind of forms are called "sticky forms"(Since the user input sticks to the form after submitting it).Try doing something like this-
<input type="text" name="email_address" value="<?php echo (isset($_POST['email_address']))?$_POST['email_address']:'';?>" id="email_address" required />
Added this ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This basically echoes out the last entry made by the user into the value field. Try doing this in each of the input tags.