Diamond shape pattern program.

<?php

$num = 10;

for($a = 1; $a <= $num; $a++)
{
    for($b = 1; $b <= $num-$a; $b++)
    {
        echo "&nbsp;&nbsp;";
    }
    for($c = 1; $c <= $a; $c++)
    {
        echo "&nbsp;*&nbsp;";
    }
    echo "<br/>";
}

for($x = 1; $x <= 9; $x++)
{
    for($y = 1; $y <= $x; $y++)
    {
        echo "&nbsp;&nbsp;";
    }
    for($z = $num; $z > $x; $z--)
    {
        echo "&nbsp;*&nbsp;";
    }
    echo "<br/>";
}

?>

How to swap two numbers without using temporary variable.

<?php
$a = 10; $b = 15;

$a = $a+$b; // $a becomes 25.
$b = $a-$b; // $b becomes 10.
$a = $a-$b; // $a becomes 15.

echo $a;
echo $b;
?>