1. Basic Php
Pengaturcaraan PHP
Pengaturcaraan PHP
What Is PHP?
PHP originally stood for Personal Home Page as it was created in 1994 by
Rasmus Lerdorf to track the visitors to his online résumé. As its
usefulness and capabilities grew (and as it started being used in more
professional situations), it came to mean "PHP: Hypertext Preprocessor."
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2. Pengaturcaraan PHP
PHP is a server-side, cross-platform technology Its cross-platform nature
means that PHP runs on most operating systems, including Windows, Unix
(and its many variants), and Macintosh
Pengaturcaraan PHP
Example
Server-Side Programming
PHP, ASP, JSP, Servlet, Perl, RXML, Python, CFML, Tcl, Miva, iHTML,
RADpage, SSI, iPerFrom, ePerl, Ruby
Client-Side Programming
HTML, Javascript, VBscript, Java Applet, CSS, DHTML
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3. Pengaturcaraan PHP
PHP is a scripting language, as
opposed to a programming
language: PHP was designed to
write Web scripts, not stand-alone
applications.
The scripts run only after an event
occurs for example, when a user
submits a form or
goes to a URL.
Pengaturcaraan PHP
Why Use PHP?
PHP is better, faster, and easier to learn
Than the alternatives.
What you get with PHP is excellent
performance, A tight integration with nearly
every database available, stability, portability,
and a nearly limitless feature set due to its
extendibility. All of this comes at no cost
(PHP is open source) and
with a very manageable learning curve.
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4. Pengaturcaraan PHP
Finally, the proof is in the pudding: PHP has seen an exponential growth
in use since its inception, overtaking ASP as the most popular scripting
language being used today. It's the most requested module for Apache
(the most-used Web server), and by the time you read this, PHP will be
on about 20 million domains.
Pengaturcaraan PHP
How PHP Works
PHP is a server-side language. This means that the code you write
in PHP resides on a host computer called a server. The server
sends Web pages to the requesting visitors (you, the client, with your
Web browser). When a visitor goes to a Web site written in PHP, the
server reads the PHP code and then processes it according to its
scripted directions. The PHP code tells the server to send the
appropriate data — HTML code — to the Web browser, which treats the
received code as it would a standard HTML page.
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5. Pengaturcaraan PHP
This differs from a static HTML site where, when a request is made,
the server merely sends the HTML data to the Web browser and there
is no server-side interpretation occurring. Hence, to the end user
and the Web browser there is no perceptible difference between what
home.html and home.php may look like, but how that page's content was
created will be significantly different.
Basic Syntax
Pengaturcaraan PHP
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6. Pengaturcaraan PHP
PHP is an HTML-embedded scripting
language. What HTML-embedded
means is that you can intermingle PHP
and HTML code within the same
script.
Pengaturcaraan PHP
To place PHP code within this document,
you surround the code with PHP tags,
either the formal and preferred or the
informal.
Anything placed within these PHP tags
will be treated by the Web server as PHP
(meaning the PHP interpreter will
process the code; text outside of the
PHP tags is immediately sent to the
Web browser).
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7. Pengaturcaraan PHP
A final consideration for your PHP
scripts is that the file must use the
proper extension.
The extension tells the server to treat
the script as a PHP page.
Most Web servers will use .html or .htm
for standard HTML pages, and
normally, .php is preferred for your
PHP scripts.
Pengaturcaraan PHP
Creating a Basic PHP Script
This first PHP script doesn't do anything,
per se, but it will demonstrate the syntax
to be used.
Step 1
Create a new document in your text
editor.
It generally does not matter what text
editor you use, be it BBEdit on the
Macintosh, the very basic Notepad or
more advanced Dreamweaver on
Windows, or vi on Linux.
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10. Sending Data
Pengaturcaraan PHP
Pengaturcaraan PHP
To build dynamic Web sites with PHP, you must know how to send data
to the Web browser. PHP has a number of built-in functions for this
purpose, the most common being echo() and print().
Either single or double quotation marks will work with either
function. Also note that in PHP all statements (a line of executed
code, in layman's terms) must end with a semicolon.
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11. Pengaturcaraan PHP
Looking for an Escape
As you might discover, one of
the complications with sending
data to the Web involves printing
single and double quotation
marks. Either of the following will
cause errors.
Pengaturcaraan PHP
There are two solutions to this problem. First, use single
quotation marks when printing a double quotation mark and
vice versa.
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12. Pengaturcaraan PHP
Or, you can escape the problematic character by preceding it with
a backslash.
Pengaturcaraan PHP
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Pengaturcaraan PHP
If you see an entirely blank page, this is probably for one of two reasons:
-There is a problem with your HTML. Test this by viewing the source
of your page and looking for HTML problems there.
- An error occurred, but display_errors is turned off in your PHP
configuration, so nothing is shown. Review your PHP configuration
documentation so that you can turn display_errors back on.
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14. Pengaturcaraan PHP
Sending HTML code
You can also use echo() and print() to send HTML code to the Web browser:
echo '<b>Hello, <font size="+2" >
world</font>!</b>';
Sending multiple chunks of data
With echo() but not print(), you can send multiple, separate chunks of data to
the Web browser using commas:
echo 'Hello, ', 'world! ';
Printing over multiple lines
Echo() and print() can both be used to print text over multiple lines.
Understanding PHP,
HTML, and White
Space
Pengaturcaraan PHP
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15. Pengaturcaraan PHP
With this in mind, there are essentially
three areas where you can affect
spacing: in your PHP scripts, in your
HTML source, and in the rendered Web
page.
The extra spaces, tabs, and blank lines
you create are generically known as
white space.
Pengaturcaraan PHP
Creating White Space
To alter the spacing of the finished
Web page, use the HTML tags <br/>
(line break, <br> in older HTML
standards) and <p></p>
(paragraph).
To alter the spacing of the HTML
source created with PHP, you can use
echo() or print() over the course of
several lines or use the newline
character (n) within double
quotation marks.
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16. Writing Comments
Pengaturcaraan PHP
Pengaturcaraan PHP
Writing the executed PHP code itself is only a part of the
programming process. A secondary but still crucial aspect to
dynamic Web site development involves documenting your code.
In HTML you can add comments using the following line:
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17. Pengaturcaraan PHP
Pengaturcaraan PHP
PHP comments are different in that
they aren't sent to the Web browser
at all, meaning they won't be
viewable to the end user, even when
looking at the HTML source. PHP
supports three comment types.
The first uses the pound or number
symbol (#). The second uses two
backslashes (//).
Both of these cause PHP to ignore
everything that follows until the end of
the line (when you press Return or
Enter). Thus, these two comments are
for single lines only. They are also
commonly used to add a comment on
the same line as some PHP code.
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A third style allows comments to run over multiple lines (/*...*/).
Pengaturcaraan PHP
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21. Pengaturcaraan PHP
What Are Variables?
Variables, in short, are containers
used to temporarily store values.
These values can be numbers, text,
or much more complex arrangements.
Variables exist at the heart of any
programming language, and
comprehending them is key to using
PHP. According to the PHP manual,
there are eight types of variables in
the language.
Pengaturcaraan PHP
Regardless of what type you are creating, all variables in PHP follow certain
syntactical rules:
- A variable's name — also called its identifier — must start with a dollar
sign ($), for example, $name.
- The variable's name can contain a combination of strings, numbers,
and the underscore, for example, $my_report1.
- The first character after the dollar sign must be either a letter or an
underscore (it cannot be a number).
- Variable names in PHP are case-sensitive. This is a very important fact.
It means that $name and $Name are entirely different variables.
- Variables can be assigned values using the equals sign (=), also called
the assignment operator.
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24. Using Strings
Pengaturcaraan PHP
Pengaturcaraan PHP
The first — arguably most important — variable type is strings. A
string is merely a quoted chunk of letters, numbers, spaces,
punctuation, and so forth. These are all strings:
- 'February 3, 2005‘
- '1,000‘
- "In watermelon sugar“
- 'Tobias'
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To make a string variable, assign a string value to a valid variable name.
Pengaturcaraan PHP
To print out the value of a string, use either echo() or print().
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To print the value of string within a context, use double quotation marks.
Pengaturcaraan PHP
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28. Pengaturcaraan PHP
Concatenating Strings
Concatenation — an important tool when creating dynamic Web sites —
is like addition for strings and is performed using the concatenation
operator: the period (.).
The $address variable now has the value SeattleWashington, which almost
achieves the desired result (Seattle, Washington).
Pengaturcaraan PHP
To improve upon this, I could write the following code so that a
space is added to the mix. The result would then be Seattle,
Washington.
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29. Pengaturcaraan PHP
Concatenation also works with strings or numbers. Either of these
statements will produce the same result Seattle, Washington 98101.
Pengaturcaraan PHP
Concatenation is commonly
used with string variables and
can be used extensively when
building databases.
Now, let's modify the
strings.php script to use this
new tool.
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31. Pengaturcaraan PHP
Pengaturcaraan PHP
Assigning new values
If you assign another value to an existing variable (say $book), the new value
will overwrite the old one. For example:
$book = 'High Fidelity';
$book = 'The Corrections';
/* $book now has a value of 'The Corrections'. */
Converting the string case
You can have PHP convert the case of your strings with: strtolower(), which
makes it entirely lowercase; strtoupper(), which makes it entirely uppercase;
ucfirst(), which capitalizes the first character; and ucwords(), which
capitalizes the first character of every word.
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32. Pengaturcaraan PHP
Others Concatenating formats
The initial example in the concatenating section could be rewritten using
either
$address = "$city, $state";
or
$address = $city;
$address . = ', ';
$address . = $state;
Using the concatenation operator with functions
The concatenation operator can be used when calling functions, like so:
$num = strlen ($first_name . $last_name);
Using Numbers
Pengaturcaraan PHP
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PHP has both integer and floating-point (decimal) number types
- 8
- 3.14
- 10980843985
- - 4.2398508
- 4.4e2
Pengaturcaraan PHP
Along with the standard arithmetic operators you can use on numbers,
there are dozens of functions. Two I'll introduce in this lesson are round()
and number_format().
Arithmetic Operators
Operator Meaning
+
Addition
-
Subtraction
*
Multiplication
/
Division
%
Modulus
++
Increment
--
Decrement
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The round() function rounds a
decimal either to the nearest
integer...
..or to a specified number
of decimal places.
Pengaturcaraan PHP
The number_format() function turns a number into the more
commonly written version, grouped into thousands using commas.
For example:
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Corresponding assignment operators
Many of the mathematical operators also have a corresponding
assignment operator, letting you create a shorthand for assigning
values. This line
$total = $total + ($total * $taxrate);
could be rewritten as
$total += ($total * $taxrate);
Pengaturcaraan PHP
Using functions inline with the echo() statement
If you use concatenation, the number_format(), or any other function,
can be used inline with an echo() statement:
echo 'You are purchasing <b>' . $quantity . '</b> widget(s) at a
cost of <b>$' . number_format ($price) . '</b> each. With tax, the total
comes to
<b>$' . number_format ($total) . '</b>.';
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39. Pengaturcaraan PHP
Constants are a specific data type
in PHP that, unlike variables, retain
their initial value throughout the
course of a script.
In fact, you cannot change the
value of a constant once it has
been set.
Constants can be assigned any
single value — a number or a
string of characters.
Pengaturcaraan PHP
To create a constant, you use the define() function instead of the
assignment operator (=) used for variables.
Notice that, as a rule of thumb, constants are named using all capitals,
although this is not required. Most importantly, constants do not use the
initial dollar sign as variables do (because, technically, constants are not
variables).
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Printing constants requires special syntax as well.
You cannot print constants using echo "Hello, USERNAME", as PHP
would just print Hello, USERNAME and not the value of the
USERNAME constant (because there's no dollar sign telling PHP that
USERNAME is anything other than literal text).
Pengaturcaraan PHP
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42. Using Single and Double
Quotation Marks
Pengaturcaraan PHP
Pengaturcaraan PHP
In PHP, values enclosed within single quotation marks will be treated literally,
whereas those within double quotation marks will be interpreted. In other
words, placing variables and special characters within double quotes will
result in their represented values printed, not their literal values.
These characters have special meanings when used within double quotation
marks.
Code Meaning
Escaped Characters " Double quotation mark
' Single quotation mark
Backslash
n Newline
r Carriage return
t Tab
$ Dollar sign
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For example, assume that you have $var = 'test';
The code echo "var is equal to $var"; will print out var is equal to test,
whereas the code echo 'var is equal to $var'; will print out var is equal
to $var.
Using an escaped dollar sign, the code echo "$var is equal to $var";
will print out $var is equal to test, whereas the code echo '$var is
equal to $var'; will print out $var is equal to $var.
This code... ...prints out...
echo "var is equal to $var"; var is equal to test
echo 'var is equal to $var'; var is equal to $var
echo "$var is equal to $var"; $var is equal to test
echo '$var is equal to $var'; $var is equal to $var
Pengaturcaraan PHP
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45. Pengaturcaraan PHP
Pengaturcaraan PHP
Single quotes can be easier than double quotes
As valid HTML often includes a lot of double-quoted attributes, it's often
easiest to use single quotation marks when printing HTML with PHP.
echo '<table width="80%" border="0"
cellspacing="2" cellpadding="3"
align="center">';
If you were to print out this HTML using double quotation marks, you would
have to escape all of the double quotation marks in the string.
echo "<table width="80%"
border="0" cellspacing="2"
cellpadding="3" align= "center">";
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