What are the best practices for handling user input in PHP to prevent errors like "Seite nicht gefunden"?

When handling user input in PHP, it is important to sanitize and validate the input to prevent errors like "Seite nicht gefunden" (Page not found). Use functions like htmlspecialchars() to prevent XSS attacks and filter_input() to validate input against predefined rules. Additionally, always check for the existence of input variables before using them to avoid undefined variable errors. 

// Sanitize and validate user input
$userInput = filter_input(INPUT_POST, 'user_input', FILTER_SANITIZE_STRING);

// Check if input is not empty before using it
if(!empty($userInput)) {
    // Process user input
} else {
    // Handle empty input error
    echo "Error: Empty input";
}

Keywords

Sanitize Validation htmlspecialchars filter_input error handling

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