Luhn test of credit card numbers: Difference between revisions

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@@ Line 1,155: / Line 1,155: @@
 =={{header|PHP}}==
+{{trans|C}}
-<lang php>function luhn($num){
+<lang php>$numbers = "49927398716 49927398717 1234567812345678 1234567812345670";
-	$sum = 0;
+foreach (split(' ', $numbers) as $n)
-	$alt = false;
+    echo "$n is ", luhnTest($n) ? 'valid' : 'not valid', '</br>';
-	for ($i = strlen($num)-1; $i>=0; $i--){
-		$n = substr($num,$i,1);
+function luhnTest($num) {
-		if($alt){
+    $len = strlen($num);
-			$n *= 2;
-			$n -= ($n > 9) ? 9 : 0;
+    for ($i = $len-1; $i >= 0; $i--) {
+        $ord = ord($num[$i]);
-		}
+        if (($len - 1) & $i) {
-		$sum += $n;
-		$alt = !$alt;
+            $sum += $ord;
+        } else {
-	}
+            $sum += $ord / 5 + (2 * $ord) % 10;
-	return ($sum%10==0);
+        }
+    }
+    return $sum % 10 == 0;
 }</lang>
+<pre>49927398716 is valid
+49927398717 is not valid
+1234567812345678 is not valid
+1234567812345670 is valid</pre>
 =={{header|PicoLisp}}==