Web Design and Programming Pt 6

iPhone DevelopmentIn this part of the Web Design and Programming tutorial, I will show you how to do anything with PHP functions. Specifically I will cover:

  • How to Create Functions
  • How to work with Function Attributes (Variables)
  • How to Pass Multiple Attributes to and from Functions
  • What Does Scope Mean (Local vs. Global)
  • What is Recursion

Part 1 of this tutorial is here Web Design and Programming. All of the code follows the video and is completely free to use in any way.

All the Code from the Video

<html>
<head>
<title><?php echo “Arrays”;?></title>
</head>

<body>

<?php
# You create functions to incapsulate tasks that you must perform repetitively
echo rand(1,100) . “<br /><br />”;

# Pass values to a function and then return the result
function addNumbers($num1,$num2)
{
return $num1 + $num2;
}

addNumbers(1,2);

# Explaining Scope : You can’t change global variables in functions
function editGlobal($globalVariable)
{
$globalVariable = 200;
}

$globalVariable = 120;
echo $globalVariable . “<br /><br />”;
editGlobal($globalVariable);
echo $globalVariable . “<br /><br />”;

# Changing Global variables by passing a reference to a variable
function editGlobal2(&$globalVariable2)
{
$globalVariable2 = 200;
}

$globalVariable2 = 120;
editGlobal2($globalVariable2);
echo $globalVariable2 . “<br /><br />”;

# Calculate tip using a default of 15%
function getTip($costSent, $tipSent=.15)
{
echo “$” . $costSent * $tipSent . “<br /><br />”;
return;
}

$cost = 100;
getTip($cost);

# Sending multiple values
function breakItUp($userInfo)
{
$userArray = explode(“,”, $userInfo);
return $userArray;
}

$userStr = “Derek,123 Main St,Pittsburgh,PA”;
$userArray = breakItUp($userStr);
foreach($userArray as $customer)
{
echo $customer . “<br />”;
}
echo “<br />”;

# Demonstrate Recursion by calculating factorials 1 * 2 * 3
function factorial($number)
{
if ($number == 1)
{
return 1; # This is the kill switch for the recursive function
}
else
{
return $number * factorial($number – 1);
}
}

echo factorial(3);

/* Explaining how recursion works
function factorial(3)
{
if (3 == 1)
{
return 1; # This is the kill switch for the recursive function
}
else
{
return 3 * factorial(3 – 1); # 3 * 2 = 6
}
}

function factorial(2)
{
if (2 == 1)
{
return 1; # This is the kill switch for the recursive function
}
else
{
return 2 * factorial(2 – 1); # The value 2 sent to the function above
}
}

function factorial(1)
{
if (1 == 1)
{
return 1; # The value 1 sent to the function above
}
else
{
return 1 * factorial(1 – 1);
}
}

*/

?>

</body>
</html>

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