PHP functions

1
PHP functions

• What are Functions?
• A function structure
• lt?php
• function myname( 1arg, 2arg,.. narg)
•    echo "Example function.\n"   return
  retval
• ?gt

2
Eg For Globals

• lt?php
• a 1b 2
• function Sum()
•    global a, b    b a b
  Sum()echo b
• ?gt

3
Eg For Statics

• lt?php
• function Tables()
•    static count 0 static x0
• y2
• count
•  x x y
• echo x ltbrgt
•   If (count lt 10)
•         Tables()   
  
• ?gt

4
Conditional Functions

• lt?
• function even()
• echo "its an even numberltbrgt"
• function odd()
• echo"its an odd numberltbrgt"
• evenfalse
• If (even TRUE)
• even()
• Else
• odd()
• ?gt

5
Nested Functions

• lt?
• function fname()
• echo "fnameltbrgt"
• function lname()
• echo "lnameltbrgt"
• //lname() not accesible
• fname()
• lname()
• ?gt
• Here lname() can only be called after calling
  fname()

6
Function Arguments

• Passing By Value
• Eg
• lt?
• function add(num)
• sumnum0num1
• echo "sumltbrgt"
• num array(0,1)
• add(num)
• echo num0
• ?gt

7
Passing By Reference

• lt?php
• function name(string)
• string . 'lname.'
• str 'fname '
• name(str)
• echo str // outputs fname lname
• ?gt

8
Use Of Default Parameters

• Ex
• lt?
• function comname (lname"Softech")
• return "company name is lnameltbrgt"
• echo comname()
• echo comname("Relyon")//prints Relyon
• ?gt

9
Continued

• lt?
• function comname (fname,
  lname"Softech")
• return "company name is fname lname"
• echo comname("Relyon")//prints Relyon
  Softech
• ?gt

10
Variable Length Argument List and Variable
Functions

• lt?
• function add(a,b)
• numargsfunc_num_args()
• if(numargsgt2)
• print("the second arg is ".func_get_arg(1)."ltbr/
  gt\n")
• print("the no of arguments passed to this
  function are numargs")
• echo"ltbrgt"
• arg_listfunc_get_args()

11
Continued

• for(i0iltnumargsi)
• echo "Argument i is " . arg_listi . "ltbr
  /gt\n"
• cab
• return c
• d'add'
• ed(2,10)
• echo "ltbrgtsumeltbrgt"
• ?gt

12
CLASSES

• A class is a collection of variables and
  functions which work on this variables.
• A simple class declaration
• Class first
• //member variables
• public a 1
• //method declaration
• public function display()
• echo this-gta//member methods

13
New

• New is used to create an instance of a class,
  a new object must be created and assigned to a
  variable.
• lt?
• Class name
• public a1
• public function display()
• echo this-gta
• b new name
• b-gtdisplay()
• ?gt

14
Extends and Constructors

• lt?php
• class parentclass
• // member declaration
• public name 'Relyon'
• // method declaration
• public function display()
• echo this-gtname

15
Continued

• class childclass extends parentclass
• function display()
• echo "Extending company\n"
• parentdisplay()
• extended new childclass()
• extended-gtdisplay()
• ?gt

16
Final

• It prevents child classes from overriding a
  method by prefixing the definition with final. If
  the class itself is being defined final then it
  cannot be extended.
• Ex
• lt? class fname
• final public function name()
• echo relyonltbrgt
• class lname extends fname
• public function name()
• echo softechltbrgt
• ?gt

17
Visibility

• Private
• Protected
• public

18
Ex For Visibility

• lt?
• class firstone
• public public "public"
• protected protected "protected"
• private private "private"
• private function privateone()
• echo "hiltbrgt"
• protected function protectedone()
• echo"protectedltbrgt"
• ob new firstone
• ob-gtpublic

19
continued

• //ob-gtprotected
• //ob-gtprivate
• //ob-gtprivateone()
• class secondone extends firstone
• public function hello()
• this-gtprotected
• this-gtprotectedone()
• cnew secondone
• c-gthello()
• ?gt

20
Scope Resolution Operator()

• lt?
• class name
• const name1 'relyonltbrgt'
• echo namename1
• class sname extends name
• public static sname "ltd"
• public static function display()
• echo parentname1
• echo selfsname
• snamedisplay()
• ?gt

21
Abstract Classes

• lt?php
• abstract class name
• // Force Extending class to define this
  method
• abstract protected function getname()
• abstract protected function
  prefixname(prefix)
• // Common method
• public function display()
• print this-gtgetname() . "\n"

22
Continued

• class fname1 extends name
• public function getname()
• return "Relyon"
• public function prefixname(prefix)
• return "prefix"
• class1 new fname1
• class1-gtdisplay()
• echo class1-gtprefixname('softech') ."\n"
• ?gt