How can you ensure proper variable handling and usage in PHP scripts to avoid errors?

To ensure proper variable handling and usage in PHP scripts to avoid errors, always initialize variables before using them, avoid using undefined variables, validate user input to prevent injection attacks, and use proper data types for variables to avoid unexpected behavior. 

// Example of proper variable handling and usage in PHP script

// Initialize variables before using them
$name = "";
$email = "";
$age = 0;

// Avoid using undefined variables
if(isset($_POST['name'])){
    $name = $_POST['name'];
}

if(isset($_POST['email'])){
    $email = $_POST['email'];
}

if(isset($_POST['age'])){
    $age = $_POST['age'];
}

// Validate user input to prevent injection attacks
$name = htmlspecialchars($name);
$email = filter_var($email, FILTER_SANITIZE_EMAIL);
$age = filter_var($age, FILTER_VALIDATE_INT);

// Use proper data types for variables
if(is_string($name) && filter_var($email, FILTER_VALIDATE_EMAIL) && is_int($age)){
    // Proceed with using the variables
    echo "Name: $name, Email: $email, Age: $age";
} else {
    echo "Invalid input data";
}

Keywords

Data validation error handling type declaration debugging exception handling

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