foreach loop not working in php code example

Example 1: for loop in php

/*
For loop in php
*/

<?php
for ($i = 0; $i < 10; $i++) {
     echo $i."<br>";
} 
?>

Example 2: math.pow in C# using loop

static float CalculatePower(float x, int y)
        {
            float temp;
            if (y == 0)
                return 1;
            temp = CalculatePower(x, y / 2);
            if (y % 2 == 0)
                return temp * temp;
            else
            {
                if (y > 0)
                    return x * temp * temp;
                else
                    return (temp * temp) / x;
            }
        }

Example 3: foreach loop not working in php

<?php
$songs = $_POST["songs"];
//$songs = Array("one","two","three");
foreach ($songs as $song) 
{
   $songStr = test_input($song);
   $songsOut .= "<li>$songStr</li>";
};

$songList = "Songs: <ol> $songsOut </ol> \r\n";
echo $songList;

function test_input($data)
{
   $data = trim($data);
   $data = stripslashes($data);
   $data = htmlspecialchars($data);
   return $data;
}

?>