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Variable Handling Functions

Introduction

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

Requirements

No external libraries are needed to build this extension.

Installation

There is no installation needed to use these functions; they are part of the PHP core.

Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

Variables Configuration Options
Name Default Changeable Changelog
unserialize_callback_func NULL PHP_INI_ALL Available since PHP 4.2.0.
For further details and definitions of the PHP_INI_* constants, see the php.ini directives.

Here's a short explanation of the configuration directives.

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.

See also unserialize().

Resource Types

This extension has no resource types defined.

Predefined Constants

This extension has no constants defined.

Table of Contents

  • debug_zval_dump — Dumps a string representation of an internal zend value to output
  • 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 the integer value of a variable
  • is_array — Finds whether a variable is an array
  • is_binary — Finds whether a variable is a native binary string
  • is_bool — Finds out whether a variable is a boolean
  • is_buffer — Finds whether a variable is a native unicode or binary string
  • 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 the type of a variable is float
  • is_int — Find whether the type of a variable is 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 — Find whether the type of a variable is string
  • is_unicode — Finds whether a variable is a unicode 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