How can PHP arrays and functions like rand() be used to prevent duplicate random numbers?

When generating random numbers using PHP's rand() function, there is a possibility of duplicates occurring. To prevent this, we can use an array to store the generated numbers and check if a newly generated number already exists in the array before adding it. If it does, we can generate a new random number until we find one that is unique. 

$randomNumbers = array();

function generateUniqueRandomNumber($min, $max) {
    global $randomNumbers;

    do {
        $randomNumber = rand($min, $max);
    } while (in_array($randomNumber, $randomNumbers));

    $randomNumbers[] = $randomNumber;

    return $randomNumber;
}

// Example usage
$randomNumber1 = generateUniqueRandomNumber(1, 10);
$randomNumber2 = generateUniqueRandomNumber(1, 10);
$randomNumber3 = generateUniqueRandomNumber(1, 10);

echo $randomNumber1 . ", " . $randomNumber2 . ", " . $randomNumber3;

Keywords

PHP arrays functions rand() prevent duplicate random numbers

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