Esecizi in php su moduli

functions.php

@@ -0,0 +1,46 @@
+
+<?php
+
+
+
+function fattoriale ($input){
+
+		if ($input == 1){
+			return 1;
+		} else {
+			return (fattoriale($input -1 ) * $input);
+		}
+
+}
+
+function isPrime($num) {
+    //1 is not prime. See: http://en.wikipedia.org/wiki/Prime_number#Primality_of_one
+    if($num == 1)
+        return false;
+
+    //2 is prime (the only even number that is prime)
+    if($num == 2)
+        return true;
+
+    /**
+     * if the number is divisible by two, then it's not prime and it's no longer
+     * needed to check other even numbers
+     */
+    if($num % 2 == 0) {
+        return false;
+    }
+
+    /**
+     * Checks the odd numbers. If any of them is a factor, then it returns false.
+     * The sqrt can be an aproximation, hence just for the sake of
+     * security, one rounds it to the next highest integer value.
+     */
+    for($i = 3; $i <= ceil(sqrt($num)); $i = $i + 2) {
+        if($num % $i == 0)
+            return false;
+    }
+
+    return true;
+}
+
+?>