CXIII. Variable Functions

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For information on how variables behave, see the Variables entry in the Language Reference section of the manual.

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�� 1. Variables Configuration Options

Name	Default	Changeable
unserialize_callback_func	""	PHP_INI_ALL

For further details and definition of the PHP_INI_* constants see ini_set().

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unserialize_callback_func string

The unserialize callback function will called (with the undefined class' name as parameter), if the unserializer finds an undefined class which should be instanciated. A warning appears if the specified function is not defined, or if the function doesn't include/implement the missing class. So only set this entry, if you really want to implement such a callback-function.

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doubleval -- Alias of floatval()
empty -- Determine whether a variable is empty
floatval -- Get float value of a variable
get_defined_vars -- Returns an array of all defined variables
get_resource_type -- Returns the resource type
gettype -- Get the type of a variable
import_request_variables -- Import GET/POST/Cookie variables into the global scope
intval -- Get integer value of a variable
is_array -- Finds whether a variable is an array
is_bool -- Finds out whether a variable is a boolean
is_callable -- Verify that the contents of a variable can be called as a function
is_double -- Alias of is_float()
is_float -- Finds whether a variable is a float
is_int -- Find whether a variable is an integer
is_integer -- Alias of is_int()
is_long -- Alias of is_int()
is_null -- Finds whether a variable is NULL
is_numeric -- Finds whether a variable is a number or a numeric string
is_object -- Finds whether a variable is an object
is_real -- Alias of is_float()
is_resource -- Finds whether a variable is a resource
is_scalar -- Finds whether a variable is a scalar
is_string -- Finds whether a variable is a string
isset -- Determine whether a variable is set
print_r -- Prints human-readable information about a variable
serialize -- Generates a storable representation of a value
settype -- Set the type of a variable
strval -- Get string value of a variable
unserialize -- Creates a PHP value from a stored representation
unset -- Unset a given variable
var_dump -- Dumps information about a variable
var_export -- Outputs or returns a parsable string representation of a variable

add a note User Contributed Notes
Variable Functions

skelley at diff dot nl
22-Sep-2001 10:55


Sorry to say Mykolas, but your definition would not be correct.





isempty() evaluates to true for NULL, 0, "", false or 'not set' for any variable, object etc. that can be set to a value.





isset() evaluates to true if the variable, object etc. exists at all, whether it is 'empty' or not.





Example:


$foo = 0;


isset($foo); //will evaluate to true.


!empty($foo); //will evaluate to false.





unset($foo);


isset($foo); //will evaluate to false.


!empty($foo); //will evaluate to false.

tapken at engter dot de
05-May-2001 03:41


This function will return a nice tree-view of an array. It's like var_dump but much prettier :-) 


Very useful to analyze an array while debugging. 


function parray($array,$prep = '') { 


/* (c) by Roland Tapken <[email protected]> */ 


$prep = "$prep|"; 


while(list($key,$val) = each($array)) { 


$type = gettype($val); 


if(is_array($val)) { 


$line = "-+ $key ($type)\n"; 


$line .= parray($val,"$prep "); 


} else { 


$line = "-&gt; $key = \"$val\" ($type)\n"; 


} 


$ret .= $prep.$line; 


} 


return $ret; 


} 





Example:


$array = array("test",2,array("foo" => "bar"), 4.23); 


echo "<pre>"; 


echo parray($array); 


echo "</pre>"; 


This will print: 


|-> 0 = "test" (string) 


|-> 1 = "2" (integer) 


|-+ 2 (array) 


| |-> foo = "bar" (string) 


|-> 3 = "4.23" (double)

Mykolas at Labas dot Com
02-Apr-2001 05:09


Definition "empty � Determine whether a variable is set" I would write "empty � Determine whether a variable is NOT set"

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CXIII. Variable Functions

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