PHP Functions

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PHP - Functions

• We have looked at a few existing PHP functions
  count, define, include, array_pop, array_push,
• We can also code user-defined functions

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PHP User-defined Functions

• function functionName( parameterList )
• // any valid PHP code

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PHP User-defined Functions

• The default is pass by value
• function foo( a )
• // a is passed by value

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PHP User-defined Functions

• Can pass by reference add in front of the
  variable name
• function foo( a )
• // a is passed by reference

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PHP Pass by reference

• function add_some_extra( string )   string
  . world'str Hello 'add_some_extra(str
  )echo str    ? Hello world

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PHP Default argument values

• function makecoffee(type "cappuccino")  
  return Cup of type"echo makecoffee( ) ?
  Cup of cappuccinoecho makecoffee("espresso")
• ? Cup of espresso

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PHP Variable length argument list

• PHP 4 and above has support for variable-length
  argument lists in user-defined functions.
• Use the func_num_args( ), func_get_arg( ),
  func_get_args( ) functions to retrieve arguments,
  ....

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PHP func_num_args

• Returns the number of arguments passed to the
  function
• function foo( )    numargs func_num_args(
  )   echo of arguments numargs\n"
  foo(17, 22, 38)    ? of arguments 3

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PHP func_get_arg

• Return an item from the argument list
• function foo( )      num func_num_args(
  )     if (num gt 2)
•      echo 2nd argument " ,
  func_get_arg(1)     foo (15, 22, 37) ?
  2nd argument 22

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PHP func_get_args

• Returns an array in which each element is the
  corresponding member of the current user-defined
  function's argument list
• function foo( )    arg_list func_get_args(
  )   for (i 0 i lt count( arg_list) i)
•        echo "Argument i is ,
  arg_listi, \n   foo(17, 22, 35)

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PHP Value returning function

• Values are returned by using the return
  statement. Any type may be returned, including
  lists and objects.
• function square( num )    return num
  numecho square(4)  ? 16

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PHP More built-in functions

• phpinfo( )
• ? info on php version,