35
ebsite Development Introducing PHP
| Date post: | 20-Dec-2015 |
| Category: |
Documents |
| View: | 236 times |
| Download: | 0 times |
Website Development
Introducing PHP
The PHP scripting language
Syntax derives from C, Java and PerlOpen SourceLinks to MySql database
How PHP is written
PHP is mixed with htmlPHP is kept between start and end tagsThe PHP interpreter, picks out the PHP code in the HTMLIt then interprets the codeIt then produces HTML
This looks very messyThe ideas are very simple thoughIt is easier than CGI languages like Perl that have to write out the HTML
: Customer browser
request service
access page
interpretset data
present html
return html
get data
get data
databasescripting language
web server
How server side scripting works
First PHP instruction
echo(“Mary had a little lamb”);
Mary had a little lamb
gets converted to
you end statements with a semi-colon
Embedding in HTML
<? php … ?>
<? … ?>
<script language="php">; ...</script>
Code is placed between start and end tags:
<html><head></head><body>
<?php echo("you can escape into php like this, "); ?>
<? echo("or simply like this, "); ?>
<script language="php">; echo("or this");</script>
</body></html>
Test
<html><head></head><body>
you can escape into php like this, or simply like this, or this</body></html>
Results in the following HTML:
Variables
Start with a $Then a letter or underscoreThen any number of letters, underscores or numbers
Examples
$customer$_1_of_the_many$go2work
PHP supports the following types:
array
floating-point numbers
integer
object
string
Example Name Result
$a + $b Addition Sum of $a and $b.
$a - $b Subtraction Difference of $a and $b.
$a * $b Multiplication Product of $a and $b.
$a / $b Division Quotient of $a and $b.
$a % $b Modulus Remainder of $a divided by $b.
Table 10-1. Arithmetic Operators
<html><head></head><body>
<?php
$h = "Hello";$w = "World";
echo($h); echo ($w);
?>
</body></html>
Test
A useful property of strings
Variables are expanded in strings
$y = 2007;echo (“Year is $y”);
echo (“Year is 2007”);
is equivalent to
<html><head></head><body><?php
$h = "Hello";$w = "World";$y = 2007;
echo("This is another $h $w $y program");
?></body></html>
Test
A loop:
for (exp1; exp2; exp3) statement;
exp1
exp2 statement
exp3
true
false
the statement can be a compound statement surrounded by { and }
<html><head></head><body>
<?php
for ($i=1; $i<10; $i=$i+1) {echo("$i ");
};?>
</body></html>
Test
Auto-increment, auto-decrement
$i++
$i--
add one to $i
subtract one from $i
<html><head></head><body>
<?php
for ($i=1; $i<15; $i++) {echo("$i ");
};?>
</body></html>
Test
Some clever stuff with loops
You can include html in the loop statement
for (exp1; exp2; exp3) {php codehtml code…
};
<html><head></head><body>
<table border="1"> <tr> <td>A simple</td> </tr> <tr> <td>table</td> </tr></table>
</body>
</html>
HTML for creating a table
<html><head></head><body>
<table border="1"><?php for ($i = 1; $i <6; $i++) { ?> <tr> <td> <?php echo("cell $i"); ?> </td> </tr><?php }; ?></table>
</body>
</html>
escape back to html
Test
<html><head></head><body>
<table border="1"> <tr> <td> cell 1 </td> </tr> <tr> <td> cell 2 </td> </tr> <tr> <td> cell 3 </td> </tr> <tr> <td> cell 4 </td> </tr> <tr> <td> cell 5 </td> </tr></table>
</body>
</html>
Results in
<html><head></head><body>
<table border="1"><?php for ($i = 1; $i <6; $i++) { ?> <tr> <td> <?php echo("cell $i"); ?> </td> </tr><?php }; ?></table>
</body>
</html>
<html><head></head><body>
<table border="1"><?php for ($i = 1; $i <10; $i++) { ?> <tr>
<?php for($j = 1; $j < 4; $j++) { ?> <td> <?php echo("cell $i, $j"); ?> </td> <?php }; ?> </tr><?php }; ?></table>
</body>
</html>Test
From here on I will introduce constructs as neededLook at the manual to find out moreLinks to the manual and other sources will be embedded in the slidesSome useful references directly into the manual follow
Chapter 11. Control Structures
if else elseif while do..while for foreach break continue switch
Table 10-3. Comparison Operators
Example Name Result
$a == $b Equal True if $a is equal to $b.
$a != $b Not equal True if $a is not equal to $b.
$a < $b Less than True if $a is strictly less than $b.
$a > $b Greater than True if $a is strictly greater than $b.
$a <= $b Less than or equal to True if $a is less than or equal to $b.
$a >= $b Greater than or equal to True if $a is greater than or equal to $b.
PHP Array Example
Test
PHP Form Handling
What this example does
• The page above contains two input fields and a submit button.
• When the user fills in this form and clicks on the submit button, the form data is sent to the "welcome.php" file.
• The "welcome.php" file looks contains these lines:
Test
PHP File Handling
• The fopen() function is used to open files in PHP.
• The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened:
File Modes
Example
• The following example generates a message if the fopen() function is unable to open the specified file:
Reading a File Line by Line
The example below reads a file line by line, until the end of file is reached:
Test
Writing to the File
So we could use the Post variable to write data entered via a form to a file. Then read it back line-by-line.
Basis for a simple guestbook.
Summary
PHP is a server side scripting languageIt is merged in with HTMLThe interpreter produces HTMLIt has a full range of variables and control structuresWe shall later look at functions and objects
