<?php
    function calc($price, $tax="")
    {
        $total = $price + ($price * $tax);
        echo "$total"; 
    }
    calc(42);    
    ?>

<?php
    function a()
    {
        function b()
        {
            echo 'I am b';
        }
        echo 'I am a';
    }
    a();
    a();
    ?>

<?php
    function a()  
    {
        function b()
        {
            echo 'I am b';
        }
        echo 'I am a';
    }
    b();
    a();
    ?>

<?php
    $op2 = "blabla";
    function foo($op1)
    {
        echo $op1;
        echo $op2;
    }
    foo("hello");
    ?><?php
        function foo($msg)
        {
            echo "$msg";
        }
        $var1 = "foo";
        $var1("will this work");
    ?>

<?php
       echo "chr(52)";
    ?>

<?php
        echo ord ("hi");
    ?>

<?php
      echo(atan(0.50));
  ?>

<?php
       define("GREETING","Hello you! How are you today?");
       echo constant("GREETING");
   ?>

<?php
        define("GREETING1","Hello you! How are you today?");
        define("GREETING2","Hello you! How are you today?");
        define("GREETING3","Hello you! How are you today?");
        echo defined("GREETING");
     ?>

<?php
    function sum($num1, $num2)
    {
        $total = $num1 + $num2;
        echo "chr($total)"; 
    }
    $var1 = "sum";
    $var1(5, 44);    
?>