Variables

 A variable is a data object whose value can be changed at any point
 in a program.  It can be any of the following:

  o  A scalar name

     A scalar is a single object that has a single value; it can be
     of any intrinsic or user-defined type.

  o  An array name

     An array is a collection of scalar elements of any intrinsic or
     derived type.  All elements must be have the same type and kind
     type parameter.

  o  A subobject designator

     A subobject is part of an object.  The following are
     subobjects:

       An array element
       An array section
       A structure component
       A substring

     For example, B(3) is a subobject (array element) designator for
     array B.  A subobject cannot be a variable if its parent object
     is a constant.


 The name of a variable is associated with a single storage
 location.

 Variables are classified by data type, as constants are.  The data
 type of a variable indicates the type of data it contains,
 including its precision, and implies its storage requirements.
 When data of any type is assigned to a variable, it is converted to
 the data type of the variable (if necessary).

 A variable is usually defined in a type declaration statement or
 DATA statement.  But during program execution, events can occur to
 cause variables to be defined or redefined (such as assignment
 statements and READ statements), or undefined (such as an I/O
 error).

 Scalar variables are assigned data types explicitly in type
 declaration statements or IMPLICIT statements, or they can have
 implicit data types.

Additional information available:

Implicit_Typing Explicit_Typing