What should be validated in PHP that can be directly influenced by the user?

In PHP, it is important to validate user input to prevent security vulnerabilities such as SQL injection, cross-site scripting, and other forms of attacks. Input validation ensures that the data provided by the user meets certain criteria before it is processed by the application. This includes checking for the correct data type, length, format, and range of values. 

// Example of validating user input in PHP
$userInput = $_POST['user_input'];

// Check if the user input is not empty
if(empty($userInput)) {
    echo "User input cannot be empty";
    // Handle the error or redirect back to the form
}

// Check if the user input is a valid email address
if(!filter_var($userInput, FILTER_VALIDATE_EMAIL)) {
    echo "Invalid email address";
    // Handle the error or redirect back to the form
}

// Additional validation checks can be added based on the specific requirements of the application

Keywords

input validation user input form validation PHP filter functions security vulnerabilities

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