PHP is a widely used scripting language for web development that is embedded within HTML. It allows for control structures, functions, and object-oriented programming. Some key points:
- PHP code is inserted into HTML pages with <?php ?> tags and can output and manipulate data.
- It supports variables, functions, classes, and inheritance to organize code and build applications.
- Variables can be defined and accessed through forms, and PHP has many built-in functions for strings, files, dates, and more.
- Classes allow for object-oriented code reuse and integration with other systems through APIs. The '->' operator accesses members but does not represent pointers.
2. PHP Hypertext Preprocessor
No joke, that’s what it stands for
Now very widely used for websites
Only three years ago it was considered a
risky alternative for development
Has a lot of community support
3. Simple PHP
PHP is meant to be invoked inline with
content
Page “escapes” into and out of a regular html
document
File extension is .php (was .php3 for version
3)
Initial use was control flow and simple
scripting
4. A quick example
<html>
<head>Test page</head>
<body>
The time is now
<?php
echo date();
?>
<hr>
</body>
</html>
5. A quick example
<html>
<head>Test page</head>
<body>
The time is now
<?php here we “jump into” php
echo date();
?> here we “jump” back out
<hr>
</body>
</html>
6. Another example
<?php
include “utilities.php”;
?>
<html>
<head>Test page</head>
<body>
<?php
if ($utils->isFriendly()) {
echo “The time is now “ . date();
} else {
echo “I will not give you the time of day”;
}
?>
<hr>
</body>
</html>
7. Another example – harder to read
<?php
include “utilities.php”;
?>
<html>
<head>Test page</head>
<body>
<?php
if ($utils->isFriendly()) {
echo “The time is now “ . date();
} else {
?>
<i>I will not give you the time of day!</i>
<?php
}
?>
<hr>
</body>
</html>
8. More PHP language details
Variables are implicitly typed
This is good
This is bad
Variables start with $
All get/post variables automatically defined
With most default server settings
With an inline directive if need be
9. Defined variable example
foo.html:
<html><head></head><body>
<form submit=“getFoo.php”>
Enter your name:
<input type=“text” name=“username”>
<input type=“submit”>
</body></html>
getFoo.php:
<html><head></head></body>
Your name is
<?php
if (!strcmp($username)) {
echo $username;
} else {
echo “not given”;
}
?>
!<br>
</body></html>
10. Function list examples
http://www.php.net/manual/en/function.strlen.
php
All string functions
Some are “obvious” to c programmers
strlen, printf, fprintf, strpos
Some are web tailored
htmlentities, htmlspecialchars
Others are new (hacky)
addcslashes, explode, soundex, quotemeta, …
11. Classes
OOP
Class structures will be defined, helping
integration with other apps and work together
APIs followed by implementation
Inheritance
Object serialization
“Magic functions”
12. Class example
class Cart
{
var $items; // Items in our shopping cart
// Add $num articles of $artnr to the cart
function add_item ($artnr, $num)
{
$this->items[$artnr] += $num;
}
// Take $num articles of $artnr out of the cart
function remove_item ($artnr, $num)
{
if ($this->items[$artnr] > $num) {
$this->items[$artnr] -= $num;
return true;
} else {
return false;
}
}
}
13. Inheritance example
Class ParentObject {
var $value;
function ParentObject() {
$this->value = 42;
}
}
class MemberObject extends ParentObject {
var $string;
function MemberObject() {
$this->string = "This is a test string.";
$this->ParentObject();
}
}
class ObjTest {
var $ObjPointer;
function ObjTest() {
$tmp = new MemberObject;
$this->ObjPointer = $tmp;
}
}
$object = new ObjTest;
echo "String Contents: " . $object->ObjPointer->string . "n";
echo "Value Contents: " . $object->ObjPointer->value . "n";
14. Back to being hacky…
“->” is NOT the same thing as it is in c++
No pointers in PHP
ONLY a member operator
Oh, you wanted pointers?
Variable variables
Yeah, you heard right
Don’t get me started…
15. Variable variables and classes example
class a {
var $b;
}
$object = new a;
$object->b = "hello";
$member_name = 'b';
echo $object->$member_name;
$object->$member_name = " world";
echo $object->$member_name;
