What are the best practices for handling user input, such as passwords, in PHP scripts to avoid errors like receiving a "false" response?

When handling user input, especially sensitive information like passwords, it is important to properly sanitize and validate the data to prevent errors such as receiving a "false" response. One common mistake is not using secure hashing functions like password_hash() to securely store passwords and password_verify() to verify them. Additionally, always use prepared statements when interacting with a database to prevent SQL injection attacks.

// Example of securely hashing and verifying passwords in PHP

// Hashing the password before storing it in the database
$password = "user_password";
$hashed_password = password_hash($password, PASSWORD_DEFAULT);

// Storing the hashed password in the database

// Verifying the password during login
$user_input_password = "user_input_password";

if (password_verify($user_input_password, $hashed_password)) {
    // Password is correct
    echo "Password is correct";
} else {
    // Password is incorrect
    echo "Password is incorrect";
}