Introduction to PHP (PHP: Hypertext Preprocessor)

Size: px

Start display at page:

Download "Introduction to PHP (PHP: Hypertext Preprocessor)"

Jack Simon
5 years ago
Views:

Versión original: Amador Durán Toro y David

José An tonio Parejo, adaptación a PHP y

1 Versión original: Amador Durán Toro y David Benavides (diciembre 2006) Última revisión: José An tonio Parejo, adaptación a PHP y traducción. Tiempo: 2h escuela técnica superior de ingeniería informática (PHP: Hypertext Preprocessor) Departamento de Lenguajes Applied Software Engineering Group November 2010 [Ángel US V7] Diseño: Amador Durán Toro ( )

2 Presentation Business Logic Data [Ángel US V7] Diseño: Amador Durán Toro ( ) Server Processing PHP PDO DBMS Web client Web server (with processing capabilities) Grupo de Ingeniería del 1

3 Basic Concepts PHP = Personal Home Page PHP is a language that allows creating scripts that are interpeted at server, creating content that is sent to the client. PHP is neither standard nor has a formal specification, but is a widely accepted Open Source technology. The pages must have the extension.php, otherwise the server does not process the PHP code A PHP page can not be properly opened as file. It must be done by means of a web server (usually Apache), usually as: /archivo.php /archivo.php /archivo.php IP/ /archivo.php PHP: Hipertext Preprocessor Grupo de Ingeniería del 2

4 Un poco de Historia de PHP: Time Año Versión PHP 1.0 PHP 2.0 PHP 3.0 PHP 4.0 PHP 5.0 Características Set of simple scripts written in Perl by Rasmus Lerdorf. Latter it were rewritten in C providing DB access capabilities. Set of scripts in beta state. It was the first version similar to current PHP, full rewrite by Andi Gutmans and Zeev Suraski. It included a stronger syntax and mimimal OO support. Performance improvements, modularity more DB Support and third party. New object model, performance improvements? PHP 6.0 Unicode support, namespaces, closures (this 2 last features were present in v5.3) Grupo de Ingeniería del 3

5 Usage of PHP: Grupo de Ingeniería del 4

PHP Objects Predefined, variables and functions of PHP and data access (PDO) are the

Predefined PHP variables are always available in PHP code, namely: $GLOBALS,

PHP incorporates a garbage collector, so we must not destroy explicitly.

6 PHP Objects Predefined, variables and functions of PHP and data access (PDO) are the elements of the language that we will use most frequently. Predefined PHP variables are always available in PHP code, namely: $GLOBALS, $_SESSION, $_REQUEST,$_GET, $_POST, $_FILES, $_COOKIE, $_SERVER, $_ENV. PHP incorporates a garbage collector, so we must not destroy explicitly. However we must create destructors if we use blocking resources, such as DB connections, printers or files. PDO Objects PDO must be created explicitly (as all ordinary PHP ) using new. We will use PHP pages to process data form sent forms, access a database and returns a response to user. Grupo de Ingeniería del 5

7 Structure of an PHP page <html> <! HTML code --> <?php PHP code?> <! HTML code --> <script language= php %> PHP code </script> <! HTML code --> </html> Moreover we can use : <??> <% %> Sevilla, noviembre de 2006 Grupo de Ingeniería del 6

8 Main features of PHP: Is an interpreted languge (script, not compiled) Is an Object based language Syntax similar to C and Java Grupo de Ingeniería del 7

9 Comments: // C-stlye Comment # Shell-style Comment /* Multi-line Java-style comment */ Grupo de Ingeniería del 8

PHP is weakly typed language Basic PHP types Strings: " Hello world!", john@rambo.

$' Can I use this symbol: \\?$ $alive = 1; //$alive is true. $alive = -1; //$alive is true. $alive = 5; //$alive is true.

10 PHP is weakly typed language Basic PHP types Strings: " Hello world!", Numbers: 12, 22.4, -5 Boolean: true, false Constant String Can I write <h1>html</h1>?' Can I use this symbol: \\? PHP casts types automatically: $alive = false; // $alive is false. $alive = 1; //$alive is true. $alive = -1; //$alive is true. $alive = 5; //$alive is true. $alive = 0; //$alive is false. $total = 5; // integer $count = "15"; // string $total += $count; // $total = 20 (integer) In PHP you can cast explicitly : Grupo de Ingeniería del 9

11 PHP operators: Boolean: and Ξ &&, or Ξ,!, xor, ==,!= Numbers: +,-,*,/,%, ==,!=, <, >. >=, <=,++,-- Identity operator === True if == and operands has the same type Operator. to append strings, you can also use.= echo y print are considered basic language constructs that allow print the value of PHP expression on the output (our web page). Grupo de Ingeniería del Software 10

$print( <p>hello world</p>\n );$

12 Our first php program: <!DOCTYPE <html> <head> <title> Hola mundo con PHP</title> </head> <body> <? print( <p>hello world</p>\n ); phpinfo();?> </body> </html> Grupo de Ingeniería del Software 11

13 PHP variables: PHP variable being with $. PHP is case-sensitive concerning to variable names In PHP variables can be used without an explicit declaration, moreover they can not be explictly declared $ABDscore = 10; PHP automatically replaces variable names by values on strings (only when using ): $name = José Antonio"; echo "Hello, $name"; Hello José Antonio Grupo de Ingeniería del Software 12

PHP Arrays: In PHP arrays can contain of different types. PHP uses associative arrays, where for each value we have a unique key (that can be a string, number, object, ).

14 PHP Arrays: In PHP arrays can contain of different types. PHP uses associative arrays, where for each value we have a unique key (that can be a string, number, object, ). The operator used to obtain the value using the key is [] : $array[key]. $states =array(0 => Alabama, 1 => Alaska, ); $echo $states[0]; Arrays can be used without initialization nor declaration arrays $states[0]= Washington ; $states[1]= New York, $echo $states[0]; Sevilla, noviembre de 2006 Grupo de Ingeniería del 13

PHP Arrays : PHP provides the function extract to expose the elements of an array as variables $shapes=array( coke' => Cilinder', orange' => sphere ); extract($shapes); // $coke and $orange are now

15 PHP Arrays : PHP provides the function extract to expose the elements of an array as variables $shapes=array( coke' => Cilinder', orange' => sphere ); extract($shapes); // $coke and $orange are now variables echo $coke; echo "<br>"; echo $orange; Interesting functions to deal with arrays: Array_push(array, elements) Array_pop(array) Array_unshift( array,elements) Array_shift( array) Array_merge( array1,array2) Array_keys( array) Array_values( array) Shuffle( array) Sevilla, noviembre de 2006 Grupo de Ingeniería del 14

$PHP functions: function name( arguments ) // each argument use $ { $local = initial_value; // fuction code return$

16 PHP functions: function name( arguments ) // each argument use $ { $local = initial_value; // fuction code return (expression); If return is not performed a value of NULL is considered as the result of the function. Grupo de Ingeniería del 15

Some interesting PHP functions: Working with Strings: printf(string, ):string formatting strlen(string): returns the length of the string Strtoupper(string) y strtolower(string) Strstr(str1,str2

17 Some interesting PHP functions: Working with Strings: printf(string, ):string formatting strlen(string): returns the length of the string Strtoupper(string) y strtolower(string) Strstr(str1,str2 ):tests if str1 is substring of str2 substr(string, position): obtain a substring Date & Time treatment: time():current instant date( format, variable): allows date formatting <? echo date("m/d/y G.i:s",$timestamp);?> checkdate(m,d, y): test if date is valid mktime(h,m,s,month,day,year):creates a new date You can add or substract seconds to dates as integers Grupo de Ingeniería del Software 16

php // Usage of headers to perform redirection Header( Location: http://www.us.es );?

18 Some interesting PHP functions: Usage of HTTP headers: Header(string): takes as argument the header to sent. enviar. <?php // Usage of headers to perform redirection Header( Location: );?> You must have in to account that Headers can t be sent after any part of the page content be <html> <? Header( Location: );?> </html > Grupo de Ingeniería del Software 17

// do { // while (expression) foreach($x as $Y){ //

block1 break; case label2 : // block2 break;.

{ // foreach($x as $Y => $Z){ /* using $Y as key

19 PHP control flow : As in Java and C++. if (expression) { // else { // while (condición) { // do { // while (expression) foreach($x as $Y){ // using arrays switch (expression) { case label1 : // block1 break; case label2 : // block2 break;... default : // block n for ($i=0; $i<=$n; $i=$i+1) { // foreach($x as $Y => $Z){ /* using $Y as key and $Z as value of each element of $X */ Grupo de Ingeniería del Software 18

20 PHP supports OO programming Classes can be defined in PHP using the following sintax: <?php class Persona { // member declaration public $name = My name'; // method declaration public function showname() { echo $this->name;?> public/protected/private: allows to define the visibility of properties and methods. $this: avaliable when a method in invoked on an object, it references the instance of the object invoked.. Grupo de Ingeniería del Software 19

$php class MiClass { function construct() { print Constructing\n"; function destruct() { print Destroying\n"; $obj = new MiClass ();?$

21 In PHP are created using the new operator PHP allows declaring constructors and desturctors <?php class MiClass { function construct() { print Constructing\n"; function destruct() { print Destroying\n"; $obj = new MiClass ();?> PHP incorporates a garbagge collector so that the destructor is invoked automatically when the object is out of scope. Grupo de Ingeniería del Software 20

22 Moreover PHP allows inheritance and Polimorfism: <?php class Student extends Person { // member declaration public $courses= array( ABD, DBD );?> protected $scores=array(8,5); // method declaration public function showscores() { echo $this->name. <BR> ; for($i=0;i<2;$i++) { echo $this->courses[i]. =.$this->scores[i]. <BR> ; Grupo de Ingeniería del Software 21

23 PHP allows declaring static and constant members using reserved words const and static. To access constant and state members we use resolution operator ::. <?php class Physics {?> const C = ; static GRAVITY = 9. 8; // $aceleration=physics:: GRAVITY; Resolut ion operator can be used with self (to access static member of the proper class) and parent (to access members and methods of parent ). Grupo de Ingeniería del Software 22

24 PHP incorporates a cloning method called clone (it invokes the private method clone() that can be overwritten by any class) PHP semantics of compare operators on (PHP v.5 or higher): $obj1 == $obj2: True if $obj1 and $obj2 are with equal values for their properties and are instances of the same class $obj1 === $obj2: True if $obj1 and $obj2 are the same instance. Grupo de Ingeniería del Software 23

25 PHP code modularization <html> ; Include functions can be used to add php code to our pages. There are four include functions: include( /path/file ) include_once( /path/file ) require( /path/file ) require_once( /path/file ) Included files are treated as HTML. <?php include($_server[ DOCUMENT_ROOT ]. /Functions.inc )?> </html> If inclusion fails, processing continues If inclusion fails, an error is generated and processing aborts File included once function f() { Functions.inc Grupo de Ingeniería del Software 24

Those functions can be used to include common content header, navigation, footer- to our web site. <? include($_server[ DOCUMENT_ROOT ]. /Header.inc );? > <? // Code?> <? include($_server[ DOCUMENT_ROOT ]. /Footer.

26 Those functions can be used to include common content header, navigation, footer- to our web site. <? include($_server[ DOCUMENT_ROOT ]. /Header.inc );? > <? // Code?> <? include($_server[ DOCUMENT_ROOT ]. /Footer.inc );?> Include and Header are absolutely different functions: Include/Require: content is imported on the page, but we use the same url and there is no new request. Header( Location: XXX ): Is a redirection, shows a new url and performs a new request. Grupo de Ingeniería del Software 25

escuela técnica superior de ingeniería informática

Tiempo: 2h escuela técnica superior de ingeniería informática Versión original: José Antonio Parejo y Manuel Resinas (diciembre 2008) Última revisión: Amador Durán y David Benavides (diciembre 2006); revisión