Instructor’s Notes
Web Data Management
PHP Sequential Processing Syntax
Web Data Management
152-155
PHP Sequential Processing Syntax
Notes
Activity
Quick Links & Text References





PHP tags in HTML
Comments
General Syntax
Declaring Variables
Output


Mathematical Calculations
String Processing

Dates


Input
Variable Scope
Pages
Pages 48 – 49
Pages
Pages 52 – 53
Pages 58 – 59
226 - 227
Pages 60 – 63
Pages 58 – 59
64 – 65
259 – 287
Pages 64 – 65
292 – 307
Pages 54 – 57
Pages 384 – 385
Inserting PHP into HTML


To include PHP in your web pages, you need to surround
the PHP commands with PHP tags
 <?php
?>
 You CANNOT include HTML tags between these
tags, only PHP commands
 Most pages have many PHP tags
The Deitel book likes to use PHP to create complete
HTML commands
<?php
echo "<h1>Welcome, $name</h1>";
?>


Note the HTML tags embedded in the string literal
(they are NOT HTML tags themselves)
Note the variable embedded in the string and that the
string is surrounded by quotes
Page 1 of 12
Instructor’s Notes
Notes

Web Data Management
PHP Sequential Processing Syntax
Activity
Murach on the other hand, prefers to embed small PHP
tags inside of the HTML
<h1>Welcome, <?php echo $name ?></h1>




Note that PHP is only used where needed.
The PHP is as short as possible
Murach explains this technique as allowing web page
(HTML) developers to develop pages without
knowing a whole lot about PHP. The PHP
programmer can work separately on complex PHP
and all the HTML programmer has to do is include it
(you'll learn about that later) and can focus on the
layout and appear of the form.
 This separates the programmer and web developer
tasks, allowing them to work on different
components of the site at the same time.
I'm not 100% convinced yet, that the two can be
completely separated, but we'll work towards that goal
and keep the PHP tags short.
Comments

Same as JavaScript
 Multiline comments /*
 Inline comments
//
*/
General Syntax



Like JavaScript, PHP IS CASE SENSITIVE
All statements end with a semicolon
All blocks of statements are surrounded by {curly
brackets}
Declaring Variables



PHP supports six data types: integer, double, boolean,
string, array and object
Variables ARE NOT declared in PHP
 You simply type the variable name the first time you
need it
 The type of the variable is determined based on the
type of data you store in the variable
 Variable types can change
Variable names start with a $ and can contain letters,
numbers, underscore
Page 2 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity
Output


In PHP, you output to the HTML that will be sent to the
client browser.
echo
echo 'My name is ' . $name;





echo command's results are inserted into the HTML
The command above would insert My name is Volker
into the HTML (assuming $name contains “Volker”)
The stuff to be echoed can be surrounded by
parenthesis, but it's not required (I normally don't)
echo's primary advantage over print is its ability to
echo a list of values (separated by commas). print can
only output one item per command.
print
print('My name is ' . $name);



The parentheses aren’t required here either but
they're almost always included in the examples I've
seen.
print's primary advantage is that it's a function, so it
returns a value. In some rare instances, that's
necessary (see book page 227)
Unless you have a reason, I'd pick one of these output
commands and stick with it (be consistent). In general,
they're interchangeable.
 Normally, we will only echo/print a single value or
(concatenated) string so the advantages of echo or
print are not a factor.
Mathematical Calculations




Same operators as JavaScript
+ - * / %
Same compound operators as JavaScript
++ -- += -= *= /= %=
Integer divided by Integer returns a double
Order of Precedence
++
-* / %
+ -
Page 3 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity
String Processing



String literals can be enclosed in either apostrophes or
quotes
 Murach suggests using apostrophes to speed up
processing
 Quotes need to be scanned for embedded variables
even if there are no embedded variables (slower)
 Remember that HTML can also use either
apostrophes or quotes. Choose your string delimiters
wisely.
Period ( . ) used for concatenation
Formatting numbers as strings
 number_format(value[, places])
 Formats numbers with commas if appropriate
 Rounds to the number of decimal places specified
 Decimal places designation is optional. If not
included, rounds to 0 decimal places
 printf(“formatting string”, value[s]);
 Use in place of print or echo (can’t be used
inside a string)
 Formatting string can include string literals and
placeholders
 Provide one value for each placeholder in
formatting string

Placeholders: source
e.g. %5.2f
▪ Starts with %
▪ Followed by field width (optional)
▪ Followed by number decimals (optional)
▪ Followed by field type
♦
%d integer
♦
%f float (number with decimals)
♦
%s
♦
Others available (see source above)
▪ Example:
printf("%s is %d years old and makes $%.2f per hour",
$empName, $empAge, $empWage);
♦
%s is replaced by the contents of $empName
♦
%d is replaced by the contents of $empAge
♦
%.2f is replaced by the contents of $empWage
♦
Always displays 2 decimals places
♦
Since width is omitted, number only
takes up as much room as it needs
Page 4 of 12
Instructor’s Notes
Notes

Web Data Management
PHP Sequential Processing Syntax
Activity
PHP allows you to embed variables inside string literals
 Usually during output (see below)
echo "My name is $name";




String must be surrounded by quotes in order for
variable to be interpreted
I don't use this much. I simply concatenate variables
to literals
Can be handy for testing
Escape characters allow you insert special or non-printing
characters into string literals
 \n (new line)
 \'
(apostrophe in a string surrounded by apostrophes)
(even works in strings surround by apostrophes)
 \” (quotes in a string surround by quotes)
 NOTE: escape characters only work in string literals
surrounded by quotes (not apostrophes)
Page 5 of 12
Instructor’s Notes
Notes

Web Data Management
PHP Sequential Processing Syntax
Activity
String functions (see web or book for details)
 empty($str)
 strlen($str)
 substr($str, $start[, $len])
 strpos($s1, $s2[, $offset]
stripos, strrpos, strripos
 Index of s2 in s1 (starting at offset)
 Adding “i” makes the search case insensitive
 Adding “r” searches in reverse
 str_replace($s1, $new, $s2)
str_replace($array, $new, $s2)
str_ireplace
 Replaces $s1 with $new in $s2
 preg_replace(‘pattern’,’repWith’, $myString)
 Use a regular express pattern to replace string
with a different string
 pattern may include /g to replace all
 chr(value) creates a single character string given an
ASCII numeric value
 ord($char) returns the ASCII value of a character
 implode and explode are used to convert an array to a
string or a string to an array (see book)
 strcasecmp($s1, $s2) compares string case insensitive
 strnatcmp($s1, $s2) compares strings of numbers
correctly (2 < 10)
 trim, ltrim, rtrim remove white space
 (int) $strvalue converts a string to an integer
(normally, this is done automatically by PHP)
 (float) $strvalue converts to a double
Page 6 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity
Dates



Timestamps are old school and will cause problems with
dates after 2038 (see 2038 problem in book or Google)
 Still used in existing web pages, but new
development should use the DateTime class
 There are functions that can convert from timestamp
to DateTime
Note PHP (in XMAPP) installs with an initial time zone
of Europe/Berlin meaning all your times (all dates for a
few hours a day) will be off by 5-6 hours. To fix this, you
have to modify the php.ini file.
 Navigate to the xampp/php folder on your USB drive
 Open php.ini in Notepad++ or Notepad
 Find (Ctrl-F) zone
 Change Europe/Berlin to America/Chicago
 Save and close
 If you have Apache (XAMPP) running, you’ll have
to stop and restart it to get the changes to take effect.
$now = new DateTime();


$now = new DateTime('2011-01-20 12:00:00');


//10:30 pm
$now must be instantiated
-> invokes a class method
$now->setDate(2011, 1, 20);
$copy = clone $now;



Alias for new DateTime( )
Can also be used with string parameter
$now->setTime(22, 30, 0);




Time is optional. If not included, set to 12:00:00 am
$now = date_create();



Instantiate the class and immediate assign current
date and time
Creates a new date variable $copy that has the same
values as $now
Can't use (just) = That simply makes two pointers
pointing to the same instance
$due->modify('+3 weeks');


Modifies the date value in $due (must be
instantiated)
See timestamp strtotime function for list of valid
modify options.
Page 7 of 12
Instructor’s Notes
Notes

Web Data Management
PHP Sequential Processing Syntax
Activity
echo $due->format('Y-m-d h:i');


Converts a date to a string and formats
Format Codes
D – Mon
l – Monday
n – 3 (month)
m – 03 (month)
M – Jan
F – January
j – 5 (day)
d – 05 (day)
Y – 2011
g – 5 (hours, 12)
G– 5 (hours, 24)
h – 05 (hours, 12)
H – 05 (hours, 24)
i – 07 (minutes)
s – 09 (seconds)
a – am/pm
A – AM/PM
T – time zone (EST)
c – 2012-01-25T13:30:15+00:00
r – Thu, 25 Jan 2012 13:30:00 +0200

NOTE: PHP Dates can be compared using relational
operators:
if($Date1 <= $Date2)
is legal in PHP (but not in JavaScript)

DateInterval Class
 Used for DateTime math
 $now->add('P10D');

Adds 10 days to $now
 $now->sub('P10D');

Subtracts 10 days from $now
 $span = $now->diff($anotherDate);

$span will be defined as a DateInterval

Determines the interval between $now and
$anotherDate
 DateIntervals can be assigned to a variable
$myInterval = new DateInterval('P10D');

DateInterval Codes
P – starts all interval strings
nY – n years
nM – n months
nW – n weeks
nD – n days
T – beginning of a time interval
nH – n hours
nM – n minutes
nS – n seconds
Page 8 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity

One interval can contain many codes
$myInterval = new DateInterval('P2WT10H30M');

2 weeks, 10 hours, 30 minutes

Note the “T” that starts the time

Formatting Intervals
 Intervals can be formatted (for display)
 Display results of a diff
echo $myInterval->format('%m months %d days');
 Interval formatting codes
%R - + or – representing future or past
%y – years
%m – months
%d – days
%h – hours
%i – minutes
%s – seconds

Any characters that appear in the format that are
not formatting codes appear as typed.
Page 9 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity
Input



Because PHP runs on a server, it has no mechanism for
getting input from a user
All PHP input comes from an HTML form POST or GET
 Murach recommends using GET when the results
page only displays data and using POST when the
results page modifies data.
The results page has access to the form variables via the
super global (always defined) arrays $_POST or $_GET
 Only one or the other array will contain values
 These arrays are associative arrays (remember from
JavaScript?). They include key/value pairs
 The keys are the determined by the names of the
HTML form objects ( name='school')
 Each form object is automatically converted to an
array element EXCEPT:
 Radio buttons (they all share the same name,
remember?)
 Check boxes are only assigned $_POST/$_GET
array elements if they are checked. They only
send their values if they are checked.
 You can use $_POST or $_GET array elements
directly in your PHP, but Murach generally transfers
values from the array to variables.
$school = $_GET['school'];

There is also a $_REQUEST super global array that
combines $_GET, $_POST, $_COOKIES
 Only one of $_GET, $_POST should contain values
 We won’t be using $_COOKIES for a while (if ever)
 Avoids need to use an If statement to figure out
which super global array was filled
 I use $_REQUEST exclusively.
Page 10 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity

Murach doesn’t mention it, but PHP comes with a
function called extract
 extract($_REQUEST);
 This command converts the key/value array pairs
into variables with the same name as the key
whose values are already set to whatever the
value was in the array
 See array notes in Unit 2
 Example:
Let’s say the form has two text fields named
firstName and lastName
Let’s further say the user enters Volker and Gaul
into these text boxes.
$_REQUEST['firstName'] contains 'Volker'
$_ REQUEST ['lastName'] contains 'Gaul'
extract($_REQUEST);
would automatically
create a variable $firstName containing 'Volker'
and another variable $lastName containing 'Gaul'

extract creates variables for every value sent
from the input form.
PHP includes a handy function: the print_r function
 print_r displays (no echo necessary) all the elements
(key/value pairs) of an array
 The results aren’t pretty, but they’re very handy for
debugging.
 I’ll often insert this command at the very beginning
of the receiving page: print_r($_REQUEST); to
verify that all my data has been transferred from the
input form and to remind me what the input field
names are.
Page 11 of 12
Instructor’s Notes
Web Data Management
Notes
PHP Sequential Processing Syntax
Activity
Variable Scope


Variables defined (used) inside PHP tags (see below) are
available to any PHP tag on the page.
 Pages often have many PHP tags
 These types of variables are considered global
variables
However, those variables are NOT accessible inside php
functions
 UNLESS, you use a separate line to designate you
want access to a global variable
global $a;



Provides access to a global variable, $a, inside a
function
Variables declared inside a function have local scope.
They are only available to that function.
Super Global variables ($_REQUEST, $_POST and
$_GET are examples, there are many others) are available
everywhere
Page 12 of 12