Add exams from exam156 to exam199

exam194/constants.php

@@ -0,0 +1,22 @@
+<?php 
+
+//Area of circle
+
+class Circle{
+    public const pi = 3.14159265359;
+
+    public function CircleArea($r){
+        return self::pi * $r *$r;
+    }
+
+}
+
+$area = new Circle;
+
+echo 'if pi is '.Circle::pi . '<br>';
+
+
+
+echo 'Area of circle is ' . $area->CircleArea(3);
+
+?>