Web Design and Programming Pt 6
In 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>