Introduction to PHP

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Introduction to PHP

• Amrish V. Chaubal
• Data Knowledge Engineering Division
• amrish_at_ncst.ernet.in

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Introduction to PHP

• PHP Hypertext Preprocessor.
• Other Names Personal Home Page, Professional
  Home Page
• Is a server side scripting language.
• Capable of generating the HTML pages
• HTML generates the web page with the static text
  and images.
• However the need evolved for dynamic web based
  application, mostly involving database usage.

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Why PHP?

• ..there are no. of server side scripting
  available like ASP, SSJS, JSP..
• PHP involves
• simplicity in scripting (..generally using the
  database)
• platform independence.
• PHP is
• primarily designed for web applications
• well optimized for the response times needed for
  web applications
• Is an open source.

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PHP Language features

• PHP language features such as control structures,
  operators, variable types, function declaration,
  class/object declaration are almost similar to
  any compiled or interpreted language such as C or
  C.

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PHP Data Type

• Three basic data types
• Integer
• Double
• String
• More data types
• Array
• Object
• PHP is an untyped language
• variables type can change on the fly.

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PHP Block

• PHP code block is embedded within the lt?php and
  ?gt tags.
• When the server encounters the PHP tags it
  switches from the HTML to PHP mode.
• There are four different ways to embed the PHP
  code
• lt?php echo(Some PHP code) ?gt
• lt? echo(Some PHP code) ?gt
• ltSCRIPT Languagephpgt echo(Some PHP code)
  lt/SCRIPTgt
• lt echo(Some PHP code) gt

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PHP Constants

• ..values that never changes
• Constants are defined in PHP by using the
  define() function.
• For e.g.
• define(NCST, National Centre for Software
  Technology)
• defined() function says whether the constant
  exists or not.

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PHP Variables

• The variables in PHP are declared by appending
  the sign to the variable name.
• For e.g
• company NCST
• sum 10.0
• variables data type is changed by the value that
  is assigned to the variable.
• Type casting allows to change the data type
  explicitly.

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PHP Variables (cont.)

• Rich set of functions for working with variable.
• For e.g
• gettype, settype, isset, unset, is_int, intval
  etc etc

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PHP Operators

• All the operators such as arithmetic, assignment,
  Comparison, and logical operators are similar to
  the operators in C and C.
• In PHP the string concatenation operator is
  denoted by ..
• For e.g.
• name My name is.myname

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PHP Statements

• IF statement
• if (ltconditiongt)
• //php code goes here
• else
• //php code goes here
• Alternative Syntax
• if(ltconditiongt)
• //html code goes here
• else
• //html code goes here
• endif

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PHP Statements (cont.)

• For loop
• for(i0i lt 10i)
• echo(the value is . i)
• Alternative Syntax
• for(i0i lt 10i)
• // html code goes here
• endfor
• While loop
• Do-While loop

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Functions

• Function declaration in PHP
• function my_func(ltparametersgt)
• //do something in the function
• for e.g.
• function sayHello()
• echo(ltBgthello amrishltBgtltBRgt)

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Functions (cont.)

• Assigning functions to the variables
• for e.g
• hello my_func
• to invoke the function my_func() through the
  variable
• hello( )
• When an argument is to be passed by reference, an
  ampersand () is placed before the parameter name
• for e.g.
• my_func(my_refvar)

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Arrays

• ..contains value set
• each element has a value, data stored in the
  element.
• And has a key by which the element can be
  referred to.

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Initializing Arrays

• No of ways to initialize the array.
• For e.g.
• ncststaff amrish
• ncststaff murali
• ncststaff narayan
• ncststaff123 amrish
• ncststaff122 murali
• ncststaff121 narayan
• ncststaff array (amrish, murali,
  narayan)
• to change the indices of the array use gt
  operator.

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Accessing the Array Elements

• The elements in the array can be accessed by
  using the list and each constructs
• for e.g
• while(list(key,value) each(countries))
• echo(valueltBRgt\n)
• current(ltarraynamegt) gives the current value
  being accessed. key(ltarraynamegt) gives the index
  of the current element that is being accessed.
• prev(ltarraynamegt) gives the previous element.
• next(ltarraynamegt) gives the next element.

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Accessing the Array Elements (cont.)

• Array_walk(ltarraynamegt,ltfunction_namegt)
• function_name is the function that is written for
  every member of an array.
• For e.g
• ncststaff array (amrish, murali,
  narayan)
• array_walk (ncststaff, printstaff)
• // function to print each element of the array
• function printstaff(names)
• echo ltBgtnameslt/BgtltBRgt\n

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Arrays (cont.)

• ncststaff array (dake gt array(amrish,
  lakshana, venkat),
• spc gt array(narayan, murali,prasad))
• creates a two dimensional array.
• Sorting Functions
• sort() sorts the elements in the numeric and
  alphabetical order.
• rsort() sorts the elements in the reverse
  order.
• asort() sorts the elements in the array without
  changing the indices.
• ksort() sorts the arrays by key.

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Classes

• Class is a template of an object and includes the
  properties and methods that describe an object
  and behavior.
• Class in PHP is defined using class statement.

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Classes (cont.)

• For e.g
• lt?
• class company
• // define the properties
• var companyname
• // define the methods
• function company(cname)
• this-gtcompanyname cname
• function getnames(idcode)
• //return the name of the employee for the
  required idcode
• ?gt

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PHP Richness

• PHP comes with myriad of options i.e. supports
  several APIs and interfaces to other programming
  tools such as
• Database connectivity.
• LDAP
• XML
• Mail protocols such as IMAP, SMTP
• Image functions
• etc.

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Support for Regular Expressions

• Not pretty things to look at and work with.
• E.g. ._at_.\\..
• PHP takes over the headache from the programmers
  for explicitly coding for pattern matching.
• Functions
• ereg() and eregi()
• ereg_replace() eregi_replace()
• split()

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Image Generation Manipulation

• PHP offers powerful set of functions for
  generating and manipulating the images.
• Rendering regular geometric figures, modifying
  images
• manipulate text, font and color and even the
  pixels in the image.
• .creating the images on the fly.

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Image Generation Manipulation (cont.)

• PHP uses the GD library for the most of the image
  functionality that it offers.
• GD library is used for generating the
  two-dimensional graphics.
• PHP APIs provides us with functions to
• Create, delete, resize and modify images.
• Draw basic geometric figures
• Manipulate text and fonts
• Manipulate colors
• Interlace and manipulate pixels
• Handle PostScript files

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Mailing functions

• Sending E-Mails
• Mail()
• Used to send simple text messages.
• Depends on the local mail delivery system.
• Using SMTP
• Accepts the e-mail for every recipient and goes
  through trouble of delivering the e-mails.
• Receiving E-Mails
• PHP works out well with the IMAP protocol.
• Rich set of support functions
• Imap_open, impa_delete, imap_close,
  imap_mail_copy, imap_mail_move etc.

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PHP-Database Connectivity

• Supports APIs for accessing large number of
  databases.
• ODBC is a standard API for accessing a database
  that has PHP support.

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PHP-Database Connectivity

• Some of Oracle 8.x functions.
• OCILogon
• OCILogoff
• OCIParse
• OCIFetch OCIFetchInto OCIFetchStatement
• OCIExecute
• OCIFreeStatement

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LDAP Support in PHP

• PHP provides LDAP APIs that allows the
  programmers to create LDAP clients by providing
  transparent access to backend LDAP directory
  servers.
• For e.g.
• Web based e-mail client.
• Telephone Directory.

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XML Support in PHP

• PHP supports a set of functions that can be used
  for writing PHP-based XML applications.
• These functions are used for parsing well formed
  XML document.

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References

• Professional PHP programming
• By Jesus Castagnetto, Chris Schollo et al
• www.phpbuilder.com
• www.php.net

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THANK YOU