# Variable handling

- Introduction
- Installing/Configuring
  - Requirements
  - Installation
  - Runtime Configuration
  - Resource Types
- Predefined Constants
- Variable handling Functions
  - boolval — Get the boolean value of a variable
  - 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
  - intval — Get the 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_countable — Verify that the contents of a variable is a countable value
  - 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_iterable — Verify that the contents of a variable is an iterable value
  - 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
  - isset — Determine if a variable is declared and is different than NULL
  - 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