PHP
Ellen Walker
CPSC 356
What is PHP?
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Stands for "PHP Hypertext Preprocessor"
Server-side scripting language
HTML-embedded
Supports 15 different databases, POP3,
IMAP, COM, CORBA
• Website: http://www.php.net
PHP alternatives
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CGI (+ back-end program)
ASP (MS Active server pages)
JSP (Sun's Java server pages)
Cold Fusion
• Most of these are not free!
PHP Operation
• PHP interpreter (on server) reads PHP file
• As it is processed, it outputs HTML to the
server
• Embedded HTML code (including
JavaScript) is passed to the server
unchanged
• Result: "view source" sees only generated
HTML, not PHP source
Embedding PHP Code
<h1>My exciting page!</h1>
<? //start php
//php code goes here
?>
PHP variables
• All variables begin with $
• Variables are not declared
• Unassigned variables have value NULL
– IsSet($var)
returns true if var is not NULL
• Variable names are case sensitive
• Reserved words (like true, while, etc.) are
not
Comments
• Three styles
– # (as in Perl)
– // (as in JavaScript)
– /* … */ (as in C)
Numbers and conversions
• Integers and floating point numbers (autotyped
when value set)
$num = 3;
//integer
$num = 3.5;
//now floating point
$num = (int) num ; //back to integer 3 again
$num2 = intval(num); //another way to do that
$num3 = 3.5; settype($num3, "integer");
//.. And a third way
Output statements
• Echo
– With no parentheses, multiple parameters,
otherwise only one
– echo "First line <br />", "Second line <br />";
• Print
– One parameter, coerced to string, returns result
– print("The value is "); print(47);
• Printf (next slide)
Printf
• Stands for "print formatted"
• Takes multiple parameters
– A format string, containing directives such as $d
(decimal), $f (float), $s (string)
• Formatting directives can include parameters between $ and
letter, e.g. $10d = decimal integer of length 10
– Values to insert for the $ directives
• Example
– printf("Your purchase of $d $s (s) costs $.2f",
$quantity, $item, $total_price);
Relational & Boolean Operators
• Relational operators (for all types)
== Same type, same value
!= Opposite of ==
>, <, >=, <= Numeric (preferred) or string comparison of
values with coercion
• Boolean operators
&&, and (Precedence of and is higher, otherwise same)
||, or (precedence of or is higher, otherwise same)
xor (exclusive or)
! (not)
Control Structures
• If
– Like C++ or Java
– Can include else if clauses (not elsif)
• While, for, do-while
– Like javascript
• Foreach
– Like Perl
Arrays
• Combine arrays with Perl hashes
• Each element has a key and a value
– Typical array: key is the integer index
– Hash-like array: key is a string
• Array names begin with $ like other
variables
Creating arrays
• $list1[0] = 17; //creates list unless it exists
• $list1[] = "hi"; //adds new last element
• $list2 = array(10,20,30,40); //creates a
traditional array of 4 elements
• $hash = array("a"=>"apple",
"b"=>"banana"); //creates a hash with 2
elements
• $list3 = array(); //creates an empty array
Accessing Array elements
• $x = $hash['a'] //gets "apple" from the
hash
• $y = $list1[1] //gets "hi" from the
traditional array
• $list ($first, $second, $third, $fourth) =
$list2; //assigns list2 to 4 individual
variables
Keys and Values
• Array_keys
– Make a traditional array of all the keys
• Array_values
– Make a traditional array of all the values
Sequential access
• current($array): current element in the array
– (initially element 0)
• next($array): increments the current element and
returns the value
$city = current($cities);
print("$city <br / >");
while($city = next($cities))
print("$city <br />");
Each (array)
• Like next but returns 2-element array of key and
value (keys are "key" and "value")
• Does not return FALSE for NULL value
while($data=each($salaries)){
$name = $data["key"];
$sal = $data["value"];
…
}
Foreach
• Shorthand for each
• Use for traditional or hash arrays
foreach($salaries as $name=>$sal)){
//process names and salaries…
}
foreach($salaries as $sal){
//process salaries without names..
}
Forms
• Forms (HTML, not PHP) collect input
• <form action=URL method={get or post}
– Get: parameters in URL
– Post: parameters not visible
– <input> and <select> statements collect data
Input tags
• Create a box that you type in:
– <input type=“text” name=“lname”>
• What you type will be passed as
“parameter” lname
• Many other types of input (checkbox, radio
buttons, etc.) -- see documentation
Select
• Create a menu
– <select name=“ssn”>
– <option value=“123456789> Mickey Mouse
</option>
–…
– <select>
• If you select an option, it is passed as
parameter “ssn”
Forms and PHP
• If method=post
– $_POST is hash with names and values from
widgets
• If method=get
– $_GET is hash with names and values from
widgets
• Example:
• $type = $_POST[‘cuporcone’]