PHP Overview CS3520 1. PHP PHP = PHP: Hypertext Preprocessor Server-side scripting language that may...
19
PHP Overview CS3520 1
-
Upload
sabina-todd -
Category
Documents
-
view
223 -
download
4
Transcript of PHP Overview CS3520 1. PHP PHP = PHP: Hypertext Preprocessor Server-side scripting language that may...
PHP OverviewCS3520
1
PHP
• PHP = PHP: Hypertext Preprocessor • Server-side scripting language that may be embedded into
HTML • One goal is to get PHP files to generate client-side code
• end up with HTML, CSS, JavaScript, other client-side code!
2
PHP --- and its output
PHP
<html> <head> <title> PHP Introduction </title></head> <body> This is HTML! <br /> <?php echo 'This is PHP! <br />'; ?> </body> </html>
Output
<html> <head> <title> PHP Introduction </title> </head> <body> This is HTML! <br /> This is PHP! <br /></body> </html>
3
More PHP<html> <head> <title> PHP Introduction </title> </head> <body> This is HTML! <br /> <?php echo 'This is PHP! <br />'; // prints to screen /* Here's a longer comment that spans multiple lines. */ ?> </body> </html>
4
PHP tags: <?php and ?> The echo command single line comment ( // ) Multiple line comment (/* and */)
PHP file names and code• End in php file extension (order.php, login.php …..)• You start all PHP scripts with the <?php open tag and end the
tag after your code with ?> .
5
Variables• PHP is a loosely-typed language • Do not need to declare the type of a variable • Type can change throughout the program
• Must start with a letter, can contain numbers, no blank spaces• scope (unless defined as global) is the script block it appears
inside of.
$x = 42; // store the value 42 in $x echo $x; // prints 42 echo $x+1; // prints 43, value of $x is still 42 $x = ‘hello!’ // type of $x can change
6
Longer example
7
<html> <body> <?php // PHP variables always start with $. $jake = 4; $allen = 3 + $jake; echo $jake, " ", $allen ?> <hr> Some html goes here.... <br> <script language="php"> // This is another wayt to enter PHP. And variable values survive between // PHP regions. echo '$jake has the value ', $jake, ".<br>"; </script> <i>This is more HTML.</i> <p> <table> <?php // There are many pre-defined variables which describe the script's // environment. echo "<tr><td><b>My URL is:</b>:</td><td>http://", $_SERVER["SERVER_NAME"], ":", $_SERVER["SCRIPT_NAME"], "</td></tr>"; echo "<tr><td><b>Your browser is</b>:</td><td>", $_SERVER["HTTP_USER_AGENT"], "</td></tr>"; echo "<tr><td><b>Your IP address is</b>:</td><td>", $_SERVER["REMOTE_ADDR"], "</td></tr>"; ?> </table></p> </body> </html>
Output previous example
My URL is:: http://puzzle.sci.csueastbay.edu:/~grewe/PHP/phpvariables.php
Your browser is:Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.90 Safari/537.36
Your IP address is: 108.243.32.249 8
4 7
Some html goes here.... $jake has the value 4.This is more HTML.
Constants• Constants can be simply defined as follows<?php // Works as of PHP 5.3.0 const CONSTANT = 'Hello World'; echo CONSTANT;?>
9
Some Pre-defined variables---see PHP documentation• There are a number of pre-defined variables in PHP. See
http://php.net for a cmoplete listing. Below is a subset of predefined variables/arrays :
• $GLOBALS• $_SERVER• $_GET• $_POST• $_FILES• $_COOKIE• $_SESSION• $_REQUEST• $_ENV•
10
Arrays• 2 kinds• Indexed are numerically indexed starting from 0. • Associative arrays associate keys to their values and are indexed by their
keys.
• The following are examples of two associative arrays, $a, $b defined followed by a numerically index array, $c.
$a = array("a" => "apple", "b" => "banana");$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");$c = array("apple", "banana"); $a['b']; //will have the value banana $c[1]; //will have the value of banana
11
Operations – similar to C++, Java
• Arithmetic operators • +, -, *, /, % (modulus – remainder after division)
• Logical AND (&&), OR (||), NOT (!) • Assignment operators • Shorthand for assignment operators: • $x += $y equivalent to $x = $x + $y • Also works with subtraction, multiplication, division, modulus,
and string concatenation
12
Equality: == OR ===
• Two “equality” operators • == tests for “equality” in value but not necessarily type • === tests for “identity” in value AND type
• == ignores the distinction between: • Integers, floating point numbers, and strings containing the same
numerical value • Nonzero numbers and boolean TRUE • Zero and boolean FALSE • Empty string, the string ‘0’ and boolean FALSE
• Any other non-empty string and boolean TRUE
13
Strings and operations• Concatenation of strings – the . operator
$a = ‘hello’; $b = ‘world’; echo $a . ‘ ‘ . $b . ‘!’; // prints ‘hello world!’
• String functions • Length: strlen() • Position of substring: strpos() • More on string functions:
http://www.w3schools.com/php/php_ref_string.asp
14
Functions• keyword funciton. • no return type for a function • parameters are defined without type
• In the first generic example, you see a function (myFunction) defined with n arguments and the last line of code returns a value.
• You would simply call this function via:
$the_value = myFunction($a1,$a2,...$an);
• Defining the funciton
<?php function myFunction($arg_1, $arg_2, /* ..., */ $arg_n) { echo "Example function.\n"; return $retval; } ?>
15
Function with array as a parameter <?php function takes_array($input) { echo "$input[0] + $input[1] = ", $input[0]+$input[1]; }?>
16
Functions and arguments• DEFAULT – pass by value
17
Functions and passing by reference• by default arguments are passed by value to a function. The
following code illustrates how to pass by reference:<?php function add_some_extra(&$string) { $string .= 'and something extra.'; }
//how to call the function above $str = 'This is a string, '; add_some_extra($str); echo $str; // outputs 'This is a string, and something extra.' ?>
18
Functions with default parameter values<?phpfunction doit($type = "txt"){ return "Default type is $type.\n";}
//now lets use the functionecho doit();echo doit(null);echo doit("jpg");?>
19
