What are some best practices for implementing a simple voting script in PHP?

Issue: Implementing a simple voting script in PHP requires ensuring that each user can only vote once and that the votes are securely stored and processed. PHP Code Snippet: 

<?php
session_start();

// Check if the user has already voted
if(isset($_SESSION['voted'])){
    echo "You have already voted.";
} else {
    // Process the vote
    $vote = $_POST['vote']; // Assuming the form has a 'vote' field

    // Store the vote in a database or file
    // For example, using a simple file-based storage
    $file = 'votes.txt';
    file_put_contents($file, $vote.PHP_EOL, FILE_APPEND);

    // Set a session variable to mark that the user has voted
    $_SESSION['voted'] = true;
    
    echo "Thank you for voting!";
}
?>

Keywords

SQL injection CSRF protection session management error handling data validation

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