PHP – Get & Post and Functions - WordPress.com
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PHP – Get & Post; Functions; and
Arrays
IS6116 – 07th February 2011
Forms and PHP
• The PHP $_GET and $_POST variables are used
to retrieve information from forms, like user
input
• Form elements in an HTML/PHP page will
automatically be available to your PHP scripts.
2
$_POST
• The $_POST variable is an array of variable
names and values sent by the HTTP POST
method
• The $_POST variable is used to collect values
from a form with method="post“
• Information sent from a form with the POST
method is invisible to others and has no limits
on the amount of information to send
3
Example - $_POST
<html>
<body>
<form action="newpage.php" method="post">
Name: <input type="text" name="name">
Age: <input type="text" name="age">
<input type="submit">
</form>
</body>
</html>
Example - $_POST continued
<html>
<head>
<title>Grab form values</title>
</head>
<body>
Welcome <?php echo $_POST["name"];?>.<br/>
You are <?php echo $_POST["age"];?> years old
</body>
</html>
$_GET
• The $_GET variable is an array of variable names
and values sent by the HTTP GET method
• The $_GET variable is used to collect values from
a form with method="get"
• Information sent from a form with the GET
method is visible to everyone (it will be displayed
in the browser's address bar) and it has limits on
the amount of information to send (max. 100
characters)
Example - $_GET
<html>
<body>
<form action="get.php" method="get">
Name: <input type="text" name="name">
Age: <input type="text" name="age">
<input type="submit">
</form>
</body>
</html>
Example - $_GET
<html>
<head>
<title>Grab form values</title>
</head>
<body>
Welcome <?php echo $_GET["name"];?>.<br/>
You are <?php echo $_GET["age"];?> years old
</body>
</html>
htmlentities
• An inbuilt function that takes a string and
returns the same string with HTML converted
into HTML entities.
• For example, the string "<script>" would be
converted to "&lt;script&gt;".
• Prevents the browser from using input values
as HTML code!
Multiform inputs
<HTML>
<HEAD>
<TITLE>Multi-page Form - Page One</TITLE>
</HEAD>
<BODY>
<p>Please fill in the following information</p>
<FORM METHOD="POST" ACTION="page2.php">
Name: <INPUT TYPE="text" SIZE="40" name="cust_name"><BR>
Email: <INPUT TYPE="text" SIZE="40" name="cust_email"><BR>
<INPUT TYPE="submit" name="submit1" value="Proceed">
</FORM>
</BODY>
</HTML>
10
<?php
$cust_name = htmlentities ($_POST['cust_name']);
$cust_email = htmlentities ($_POST['cust_email']);
?>
<HTML>
<HEAD>
<TITLE>Multi-page Form - Page Two</TITLE>
</HEAD>
<BODY>
<p>Please fill in the following information</p>
page2.php
<FORM METHOD="POST" ACTION="final.php">
Address: <INPUT TYPE="text" SIZE="50" name="cust_address"><br/>
Phone: <INPUT TYPE="text" SIZE="20" name="cust_phone"><br/>
<INPUT TYPE="hidden" name="cust_name"
VALUE="<?php echo $cust_name; ?>">
<INPUT TYPE="hidden" name="cust_email"
VALUE="<?php echo $cust_email; ?>">
<INPUT TYPE="submit" name="submit2" value="Proceed">
</FORM>
</BODY>
</HTML>
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final.php
<?php
$cust_name = htmlentities($_POST['cust_name']);
$cust_email = htmlentities($_POST['cust_email']);
$cust_address = htmlentities($_POST['cust_address']);
$cust_phone = htmlentities($_POST['cust_phone']);
?>
<HTML>
<HEAD>
<TITLE>Multi-page Form - Final</TITLE>
</HEAD>
<BODY>
<p>You filled in:</p>
Name: <?php echo $cust_name; ?><br/>
Email: <?php echo $cust_email; ?><br/>
Address: <?php echo $cust_address; ?><br/>
Phone: <?php echo $cust_phone; ?><br/>
</BODY>
</HTML>
12
Functions
• 2 types:
– Built in functions
– Custom defined functions
• Functions minimize the amount of repetition
of code.
• function consists of function name followed
by parentheses. Some functions may need
values passed to it.
Built in Functions
• Thousands of built in functions. Can be found
on w3schools.com or php.net
• Example built-in function: strtoupper()
• strtoupper(“php on Mondays”);
• converts string “php on Mondays” to “PHP ON
MONDAYS”
Custom Defined Functions
• Syntax:
• function name_of_function($arg1, $arg2)
{
//code of the function
}
Note: You can but are not required to include
arguments within the parentheses!
Simple function without arguments
• function say_hello()
{
echo “<p>Hello everybody!</p>”;
}
• To call the function:
say_hello();
Function requiring an Argument
• <?php
function printBR($txt)
{
echo $txt.”<br/>”;
}
printBR(“Line one!”);
printBR(“Line two!”);
?>
Function to return a value (s)
• <?php
function addNums($first, $second)
{
$result = $first + $second;
return $result;
}
echo addNums(10, 3);
//Sends 10 and 3 as arguments to the addNums
function and will print 13
Variable Scope
• Variables declared within functions remain
local to those functions (i.e. they will not be
accessible outside the function)
• function $test(){
$testvariable = “this is a test variable”;
}
echo “test variable is “.$testvariable;
function $test(){
$testvariable = “this is a test variable”;
}
echo “test variable is “.$testvariable;
• Will create an error!
Variable scope continued
• Variables defined outside functions are
inaccessible within functions by default
• Following will output an error!
$testvariable = “this is a test variable”;
function $test(){
echo $testvariable;
}
test();
Variable Scope Continued
• Use global statement to access variable in a function
that has been defined outside the said function
$testvariable = “this is a test variable”;
function $test(){
global $testvariable;
echo $testvariable;
}
test();
Passing by value & by reference
• When passing arguments to functions, they
are stored as copies
• Any changes made to the variable within the
body of a function are local to that function
and do not extend to outside
Passing by Value - Example
• <?php
function addFive($num){
$num += 5;
}
$originalNum = 10;
addFive($orignalNum);
echo $originalNum; //Outputs 10
?>
Passing by Reference - Example
• <?php
function addFive(&$num){
$num += 5;
}
$originalNum = 10;
addFive($orignalNum);
echo $originalNum; //Outputs 15
?>
Passing by Reference gives access to the actual variable
that is passed rather than just a copy of the variable as
per passing by Value
Arrays
• Variables typically store one value at a time (i.e. a
variable may store a single colour such as red,
blue, green, or some other colour
• However, where you may need to store a list of
values in a variable rather than just one value an
array is suitable
• E.g. a normal variable may store a value for the
colour variable whereas an array facilitates
storing a list of values for an array
Creating arrays
• number of ways to create arrays
– array() function (typically used when populating
the values of array in one go!)
– the array operator [] (typically to store one value
initially allowing for additional values later)
Array Example
• $colours = array (“red”, “blue”, “green”,
“yellow”, “black”, “purple”);
• Same as: $colours[] = “red”;
$colours[] = “blue”;
$colours[] = “green”;
and so on....
Associative Arrays
• A variable array capable of storing various
different elements and associated values
• $person = array(“name” => “John”, “age” =>
10, “occupation” => “PHP Coder”);
• $person[‘age’] = 10;
$person[‘name’ = “John”;
• echo $person[‘age’];
Multidimensional Arrays
• Facilitates storing arrays of arrays!
• Extends beyond the associative array to store
multiple sets of associative arrays
Multidimensional Example
• <?php
$person = array(
array(“name” => “John”, “age” => 19),
array(“name” => “Mary”, “age” => 30),
array(“name” => “Aine”, “age” => 23)
);
?>
Multidimensional Arrays
• each of the array elements store starting at an
index value of 0
• for instance:
– echo $person[0];
– echo $person[1];
– and so on and on and on!
Multidimensional Arrays
• foreach ($person as $p) {
while (list($n, $a) = each ($p)) {
echo “Name: “.$n.”\n Age: ”.$a.”<br/>”;
}
}
• Output:
Name: John
Age: 19
Name: Mary
Age: 30
Name: Aine
Age: 23
In built functions suitable for Arrays
•
•
•
•
•
•
count()
sizeof()
each()
list()
foreach()
array_push() - Adds 1 or more elements to
the end of an existing array
– e.g. array_push($person, “Harry”, 24);
• More array related functions – can be found at
php.net/array or w3schools.com and so on
