How can PHP handle form input errors and redirect the user back to the form for corrections?

When handling form input errors in PHP, you can validate the user input and if errors are found, redirect the user back to the form to make corrections. This can be achieved by setting error messages in session variables, redirecting back to the form page, and displaying the error messages to the user. 

<?php
session_start();

if($_SERVER["REQUEST_METHOD"] == "POST"){
    // Validate form input
    $errors = array();

    // Check for errors in form input
    if(empty($_POST['username'])){
        $errors['username'] = "Username is required";
    }

    // Check for more errors...

    if(!empty($errors)){
        $_SESSION['errors'] = $errors;
        header("Location: form.php");
        exit();
    }
}

// Display form with errors
if(isset($_SESSION['errors'])){
    $errors = $_SESSION['errors'];
    unset($_SESSION['errors']);
    // Display error messages next to form fields
}
?>

Keywords

PHP form input errors redirection validation error handling

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