Created
March 11, 2023 06:02
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<?php | |
function main() { | |
$len = 0; | |
$divisor = 10; | |
$ccn; | |
// Query user for card details | |
do | |
{ | |
$ccn = (int)readline("Enter Card Number: "); | |
} | |
while ($ccn < 0); | |
$cardNumber = $ccn; | |
// Computing credit card length | |
while($cardNumber != 0) | |
{ | |
$cardNumber = intdiv($cardNumber, 10); | |
$len++; | |
} | |
$cardNumber = $ccn; | |
// luhns Algorithm | |
$sum = 0; | |
for ($i = 1; $i <= $len; $i++) | |
{ | |
$digit = $cardNumber % 10; | |
if ($i % 2 == 0) | |
{ | |
if ($digit * 2 > 9) | |
{ | |
$sum += $digit * 2 - 9; | |
} | |
else | |
{ | |
$sum += $digit * 2; | |
} | |
} | |
else | |
{ | |
$sum += $digit; | |
} | |
$cardNumber = intdiv($cardNumber, 10); | |
} | |
for ($j = 0; $j < $len - 2; $j++) | |
{ | |
$divisor = $divisor * 10; | |
} | |
$cardNumber = $ccn; // prevents exhausting original card number in loop | |
$firstDigit = intdiv($cardNumber, $divisor); | |
// Reduces divisor by 10 | |
$divisor = round($divisor / 10); // Proper division - like C | |
$firstTwoDigits = intdiv($cardNumber, $divisor); | |
if ($sum % 10 == 0) | |
{ | |
if ($len == 15 && ($firstTwoDigits == 34 || $firstTwoDigits == 37)) | |
{ | |
printf("AMEX\n"); | |
} | |
else if ($len == 16 && ($firstTwoDigits > 50 && $firstTwoDigits < 56)) | |
{ | |
printf("MASTERCARD\n"); | |
} | |
else if (($len == 19 || $len == 13 || $len == 16) && ($firstDigit == 4)) | |
{ | |
printf("VISA\n"); | |
} | |
else | |
{ | |
printf("INVALID\n"); | |
} | |
} | |
else | |
{ | |
printf("INVALID\n"); | |
} | |
} | |
// Run Main | |
main() | |
?> |
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