Introduction to php functions and arrays

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By ProgrammerBlog.net
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http//programmerblog.net Introduction to
Functions and Arrays
2
PHP Fundamentals Functions
By ProgrammerBlog.net
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• A set of constructs which allow the programmer to
  break up their code into smaller, more
  manageable, chunks which can be called by name
  and which may or may not return a value.
• function function_name (parameters)
• function-body
• function helloWorld()
• echo "HelloWorld" //No out put is
  shown

3
Functions Passing Parameters
By ProgrammerBlog.net
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• Passing parameters by value
• function salestax(price,tax)
• total price (price tax
• echo "Total cost total"
• salestax(15.00,.075)
• pricetag 15.00
• salestax .075
• salestax(pricetag, salestax)

4
Functions Passing Parameters
By ProgrammerBlog.net
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• Passing parameters by reference
• cost 20.00
• tax 0.05
• function calculate_cost(cost, tax)
• // Modify the cost variable
• cost cost (cost tax)
• // Perform some random change to the tax
  variable.
• tax 4
• calculate_cost(cost,tax)
• echo "Tax is ". tax100."ltbr /gt"
• echo "Cost is ". cost."ltbr /gt"

5
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Functions Default Argument Values

• Default values are automatically assigned to the
  argument if no other value is provided
• function salestax(price,tax.0575)
• total price (price tax)
• echo "Total cost total"
• price 15.47
• salestax(price)

6
By ProgrammerBlog.net
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Functions Optional Arguments

• Certain arguments can be designated as optional
  by placing them at the end of the list and
  assigning them a default value of nothing .
  
• function salestax(price, tax"")
• total price (price tax)
• echo "Total cost total"
• salestax(42.00)
• function calculate(price,price2"",price3
  "")
• echo price price2 price3
• calculate(10,"", 3)

7
By ProgrammerBlog.net
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Functions Returning Values from a Function

• You can pass data back to the caller by way of
  the return keyword.
• function salestax(price,tax.0575)
• total price (price tax)
• return total
• total salestax(6.50)
• Returning Multiple Values
• function retrieve_user_profile()
• user "Jason"
• user "jason_at_example.com"
• return user
• list(name,email) retrieve_user_profile()
  
• echo "Name name, email email "

8
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Functions Nesting Functions

• defining and invoking functions within
  functions
• function salestax(price,tax)
• function convert_pound(dollars,
  conversion1.6)
• return dollars conversion
• total price (price tax)
• echo "Total cost in dollars total.
  Cost in British pounds "
• . convert_pound(total)
• salestax(15.00,.075)
• echo convert_pound(15)

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Functions Recursive Functions
By ProgrammerBlog.net
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functions that call themselves function
nfact(n) if (n 0)
return 1 else
return n nfact(n - 1)
//call to function nfact(num)
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Functions Variable Functions
By ProgrammerBlog.net
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• Functions with parameters on run time
• function hello()
• if (func_num_args()gt0)
• argfunc_get_arg(0) //Thefirstargumentisatposi
  tion0
• echo "Helloarg"
• else
• echo "HelloWorld"
• hello("Reader") //Displays"HelloReader"
• hello() //Displays"HelloWorld"

11
By ProgrammerBlog.net
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Server Side Includes (SSI) include() function

• Include function
• You can insert the content of one PHP file into
  another PHP file before the server executes it,
  with the include() or require() function. (e.g.
  Header, Menu, footer)
• The include() function takes all the content in a
  specified file and includes it in the current
  file
• include() generates a warning, but the script
  will continue execution
• lthtmlgt
• ltbodygt
• lt?php include("header.php") ?gt
• lth1gtWelcome to my home page!lt/h1gt
• ltpgtSome text.lt/pgt
• lt/bodygt
• lt/htmlgt

12
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Server Side Includes (SSI) include() function

• lthtmlgt
• ltbodygt
• ltdiv class"leftmenu"gt
• lt?php include("menu.php") ?gt
• lt/divgt
• lth1gtWelcome to my home page.lt/h1gt
• ltpgtSome text.lt/pgt
• lt/bodygt
• lt/htmlgt

13
By ProgrammerBlog.net
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Server Side Includes (SSI) include() function
lthtmlgt ltbodygt ltdiv class"leftmenu"gt lta
href"/default.php"gtHomelt/agt lta
href"/tutorials.php"gtTutorialslt/agt lta
href"/references.php"gtReferenceslt/agt lta
href"/examples.php"gtExampleslt/agt lta
href"/about.php"gtAbout Uslt/agt lta
href"/contact.php"gtContact Uslt/agt lt/divgt lth1gtWelc
ome to my home page!lt/h1gt ltpgtSome
text.lt/pgt lt/bodygt lt/htmlgt
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By ProgrammerBlog.net
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Server Side Includes (SSI) require() function

• Require function
• require() generates a fatal error, and
  the script will stop
• include() generates a warning, but the script
  will continue execution
• lthtmlgt
• ltbodygt
• lt?php
• require("wrongFile.php")
• echo "Hello World!"
• ?gt
• lt/bodygt
• lt/htmlgt
• It is recommended to use the require() function
  instead of include(), because scripts should not
  continue after an error.

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PHP Built In Functions
By ProgrammerBlog.net
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• Math functions
• http//www.w3schools.com/php/php_ref_math.asp
• pi() Returns the value of PI
  
• pow() Returns the value of x to the power of y
• rad2deg() Converts a radian number to a degree
• rand() Returns a random integer
• round() Rounds a number to the nearest integer
• sin() Returns the sine of a number
• sinh() Returns the hyperbolic sine of a number
• sqrt() Returns the square root of a number
• srand() Seeds the random number generator
• tan() Returns the tangent of an angle
• tanh()
• abs() Returns the absolute value of a number

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PHP Built In Misc. Functions
By ProgrammerBlog.net
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• Constants
• M_LN10 Returns the natural logarithm of 10
  (approx. 2.302)
• M_PI Returns PI (approx. 3.14159)
• M_SQRT2 Returns the square root of 2 (approx.
  1.414)
• Miscellaneous Functions
• Strlen Returns length of a string
  
• count() Returns the count of an array.
• Strtolower strtolower() to lower
  case.
• strtoupper() strtoupper() convert
  string to upper case

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PHP Fundaments - Arrays
By ProgrammerBlog.net
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• Arrays are ordered collections of items, called
  elements
• Each element has a value, and is identified by a
  key that is unique to the array It belongs to
• In PHP, there are three kind of arrays
• Numeric array - An array with a
  numeric index
• Associative array - An array where each
  ID key is associated with a value
• Multidimensional array - An array containing one
  or more arrays.
• a array()
• state0 "Delaware"
• a array (10, 20, 30)
• a array (a gt 10, b gt 20, cee gt 30)
• a array (5 gt 1, 3 gt 2, 1 gt 3,)

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PHP Fundaments - Arrays
By ProgrammerBlog.net
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• Numeric Arrays
• A numeric array stores each array element with a
  numeric index.
• cars array("Saab","Volvo","BMW","Toyota")
• cars0"Saab" //2nd way of declaring
  arrays
• cars1"Volvo"
• cars2"BMW"
• cars3"Toyota"
• echo cars0 . " and " . cars1 . " are
  Swedish cars."
• Associative Arrays
• An associative array, each ID key is associated
  with a value.
• ages array(John"gt32, Jane"gt30,
  David"gt34)
• agesJohn ' "32"
• agesJane ' "30"
• agesDavid ' "34"
• states array (0 gt "Alabama", "1" gt
  "Alaska"..."49" gt "Wyoming") //numeric
• states array ("OH" gt "Ohio", "PA" gt
  "Pennsylvania", "NY" gt "New York")

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PHP Fundaments - Arrays
By ProgrammerBlog.net
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• Multidimensional Arrays
• Arrays of arrays, known as multidimensional
  arrays
• In a multidimensional array, each element in the
  main array can also be an array.
• cars array ( Toyota"gtarray ( Corolla, "
  Camry, "Toyota 4Runner ),
• Suzuki"gtarray ( Vitara ),
• Honda"gtarray ( "Accord, Sedan,
  Odyssey ) )
• echo "Is " . cars Toyota '2 . " a member
  of the Toyota cars?
• Is Toyota 4Runner a member of the Toyota cars?
• states array (
• "Ohio" gt array ("population" gt
  "11,353,140", "capital" gt "Columbus"),
• "Nebraska" gt array ("population" gt
  "1,711,263", "capital" gt "Omaha")
• )

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PHP Fundaments Printing Arrays
By ProgrammerBlog.net
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• print_r() and var_dump()
• var_dump
• var_dump() outputs the data types of each value
• var_dump() is capable of outputting the value of
  more than one variable
• var_dump(states)
• a array (1, 2, 3)
• b array (a gt 1, b gt 2, c gt 3)
• var_dump (a b) // creates union of arrays
• If 2 arrays have common elements and also share
  same string or numeric key will appearance in
  result or output
• print_r
• print_r can return its output as a string, as
  opposed to writing it to the scripts standard
  output
• print_r(states)

21
By ProgrammerBlog.net
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PHP Fundaments Comparing - Counting Arrays

• a array (1, 2, 3)
• b array (1 gt 2, 2 gt 3, 0 gt 1)
• c array (a gt 1, b gt 2, c gt
  3)
• var_dump (a b) // True
• var_dump (a b) // False
  returns true only if the array contains the
• 
  same key/value pairs in the same
  order
• var_dump (a c) // True
• var_dump (a c) // False
• a array (1, 2, 4)
• b array()
• c 10
• echo count (a) // Outputs 3
• echo count (b) // Outputs 0
• echo count (c) // Outputs 1
• is_array() function echo in_array (a, 2) //
  True

22
By ProgrammerBlog.net
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By ProgrammerBlog.net
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PHP Fundaments Flipping and Reversing , Range

• array_flip()
• Exchanges all keys with their associated values
  in an array
• trans  array("a" gt 1, "b" gt 1, "c" gt 2)tr
  ans  array_flip(trans)print_r(trans)
• Output Array ( 1 gt b 2 gt c )
• array_reverse()
• Return an array with elements in reverse order
• array_values()
• array_values Return all the values of an array
• array  array("size" gt "XL", "color" gt "gold")
  print_r(array_values(array))
• array_keys Return all the keys of an array
• range()
• The range() function provides an easy way to
  quickly create and fill an array consisting of a
  range of low and high integer values.
• die range(0,6) // Same as specifying
  die array(0,1,2,3,4,5,6)

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PHP Fundaments Sorting Arrays
By ProgrammerBlog.net
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• There are many functions in PHP core that provide
  various methods of sorting array contents.
• sort
• array array(a gt foo, b gt bar, c gt
  baz)
• sort(array)
• var_dump(array)
• asort //to maintain key
  association,
• - array array(a gt foo, b
  gt bar, c gt baz)
• asort(array)
• var_dump(array)
• rsort,
• arsort // sorting an array in
  descending order

24
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PHP Fundaments Arrays as Stack and Queues

• Stack Last in First Out.
• array_push()
• stack array()
• array_push(stack, bar, baz)
• var_dump(stack)
• array_pop()
• states array("Ohio","New York","California","Te
  xas")
• state array_pop(states) // state "Texas"
• Queues
• array_shift, Shift an element off the beginning
  of array
• array_unshift - Prepend one or more elements to
  the beginning of an array
• stack array(qux, bar, baz)
• first_element array_shift(stack)
• var_dump(stack)
• array_unshift(stack, foo)
• var_dump(stack)

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Super Globals
By ProgrammerBlog.net
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• Several predefined variables in PHP are
  "superglobals", which means they are available in
  all scopes throughout a script. There is no need
  to do global variable to access them within
  functions or methods.
• GLOBALS
• _SERVER
• _GET
• _POST
• _FILES
• _COOKIE
• _SESSION
• _REQUEST
• _ENV

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Features Super Globals
By ProgrammerBlog.net
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• GLOBALS References all variables available in
  global scope
• lt?phpfunction test()     foo  "local variable
  "    echo 'foo in global scope ' . GLOBALS"
  foo" . "\n"    echo 'foo in current scope ' .
   foo . "\n"foo  "Example content"test()
  ?gt
• _SERVER -- HTTP_SERVER_VARS deprecated
  Server and execution environment information
• lt?phpecho _SERVER'SERVER_NAME'?gt

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Super Globals
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• _ENV -- HTTP_ENV_VARS deprecated
  Environment variables
• lt?phpecho 'My username is ' ._ENV"USER" . '!'
  ?gt
• ip  _SERVER'REMOTE_ADDR'

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Super Globals
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