What best practices should PHP developers follow when handling user input, such as POST variables, to avoid errors or unexpected behavior?

When handling user input in PHP, developers should always sanitize and validate the data to prevent security vulnerabilities and unexpected behavior. One common practice is to use PHP functions like filter_input() or htmlentities() to sanitize input and validate it against expected formats. Additionally, developers should use prepared statements when interacting with databases to prevent SQL injection attacks. 

// Example of sanitizing and validating user input from a POST variable
$userInput = filter_input(INPUT_POST, 'user_input', FILTER_SANITIZE_STRING);

if ($userInput) {
    // Process the sanitized input
} else {
    // Handle invalid input
}

Keywords

validation sanitization htmlspecialchars filter_input error handling

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