PHP verification credit card number example

How does PHP verify whether there is a problem with the credit card number? This article mainly introduces the PHP implementation of the Luhn algorithm to verify whether the credit card number is valid, and analyzes the implementation of the Luhn algorithm in PHP and related application skills through examples. I hope to be helpful.

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 results

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

The following is a more concise code:

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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