What are some strategies for efficiently comparing and storing user IDs to prevent duplicate notifications in PHP?

When sending notifications to users, it's important to efficiently compare and store user IDs to prevent duplicate notifications. One strategy is to maintain a list of user IDs that have already received a notification and check against this list before sending a new notification. This can be done using an array or a database table to store the user IDs. 

// Sample code to efficiently compare and store user IDs to prevent duplicate notifications

// Array to store user IDs that have already received a notification
$notifiedUsers = [];

// Function to check if a user has already been notified
function userAlreadyNotified($userId, $notifiedUsers) {
    return in_array($userId, $notifiedUsers);
}

// Function to send notification to a user
function sendNotification($userId, &$notifiedUsers) {
    if (!userAlreadyNotified($userId, $notifiedUsers)) {
        // Send notification code here

        // Add user ID to the list of notified users
        $notifiedUsers[] = $userId;
    }
}

// Example of sending notification to user with ID 123
sendNotification(123, $notifiedUsers);

Keywords

PHP user IDs duplicate notifications efficient comparison storage.

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