PHP uses Luhn algorithm to verify whether the credit card number is valid

This article mainly introduces the PHP implementation of checking whether the credit card number is valid through the Luhn algorithm. It analyzes the implementation of the Luhn algorithm in PHP and related application techniques with examples. It has certain reference value. Friends in need can refer to it

The example in this article describes how PHP implements the Luhn algorithm to verify whether a credit card number is valid. The specific implementation method is as follows:

$numbers = "49927398716 49927398717 1234567812345678 1234567812345670";
foreach (split(' ', $numbers) as $n)
  echo "$n is ", luhnTest($n) ? &#39;valid&#39; : &#39;not valid&#39;, &#39;</br>&#39;;
 
function luhnTest($num) {
  $len = strlen($num);
  for ($i = $len-1; $i >= 0; $i--) {
    $ord = ord($num[$i]);
    if (($len - 1) & $i) {
      $sum += $ord;
    } else {
      $sum += $ord / 5 + (2 * $ord) % 10;
    }
  }   
  return $sum % 10 == 0;
}

Running result

49927398716 is valid
49927398717 is not valid
1234567812345678 is not valid
1234567812345670 is valid

The following is a more concise code:

The code is as follows:

function luhn_test($num) {
    $str = '';
    foreach( array_reverse( str_split( $num ) ) as $i => $c ) $str .= ($i % 2 ? $c * 2 : $c );
    return array_sum( str_split($str) ) % 10 == 0;
}
foreach (array('49927398716','49927398717','1234567812345678','1234567812345670') as $n)
echo "$n is ", luhn_test($n) ? &#39;valid&#39; : &#39;not valid&#39;, "</br>\n";

The output result is as follows

49927398716 is valid
49927398717 is not valid
1234567812345678 is not valid
1234567812345670 is valid

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