Question

How to mask a number with stars except the last 4 digits in PHP

Answer 1

function mask_number_with_stars_except_the_last_4_digits($cardNumber) {
    $last4Digits = substr($cardNumber, -4);
    $maskedNumber = str_pad($last4Digits, strlen($cardNumber), '*', STR_PAD_LEFT);
    
    return $maskedNumber;
}

$cardNumber = '9003125334656789';

$maskedNumber = mask_number_with_stars_except_the_last_4_digits($cardNumber);

echo $maskedNumber;



/*
run:

************6789

*/

 

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Answer 2

function mask_number_with_stars_except_the_last_4_digits($cardNumber) {
    $maskedNumber = str_repeat('*', MAX(4, strlen($cardNumber)) - 4) . substr($cardNumber, -4);
     
    return $maskedNumber;
}
 
$cardNumber = '9003125334656789';
 
$maskedNumber = mask_number_with_stars_except_the_last_4_digits($cardNumber);
 
echo $maskedNumber;
 
 
 
/*
run:
 
************6789
 
*/

 

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