POINTER - Integer

POINTER (pointer,pointee) [,(pointer,pointee)] . . .

The following are pointer rules and behavior:

• Two pointers can have the same value, so pointer aliasing is allowed.

• When used directly, a pointer is treated like an integer variable. On IA-32 architecture, a pointer occupies one numeric storage unit, so it is a 32-bit quantity (INTEGER(4)). On Intel® 64 architecture, a pointer occupies two numeric storage units, so it is a 64-bit quantity (INTEGER(8)).

• A pointer cannot be a pointee.

• A pointer cannot appear in an ASSIGN statement and cannot have the following attributes:

  ALLOCATABLE	INTRINSIC	POINTER
  EXTERNAL	PARAMETER	TARGET

  A pointer can appear in a DATA statement with integer literals only.

• Integers can be converted to pointers, so you can point to absolute memory locations.

• A pointer variable cannot be declared to have any other data type.

• A pointer cannot be a function return value.

• You can give values to pointers by doing the following:

  • Retrieve addresses by using the LOC intrinsic function (or the %LOC built-in function)

  • Allocate storage for an object by using the MALLOC intrinsic function (or by using malloc(3f) on Linux* and macOS* systems)

  For example:

  Using %LOC:                  Using MALLOC:
  
  INTEGER I(10)                INTEGER I(10)
  INTEGER I1(10) /10*10/       POINTER (P,I)
  POINTER (P,I)                P = MALLOC(40)
  P = %LOC(I1)                 I = 10
  I(2) = I(2) + 1              I(2) = I(2) + 1

• The value in a pointer is used as the pointee's base address.

The following are pointee rules and behavior:

• A pointee is not allocated any storage. References to a pointee look to the current contents of its associated pointer to find the pointee's base address.

• A pointee cannot be data-initialized or have a record structure that contains data-initialized fields.

• A pointee can appear in only one integer POINTER statement.

• A pointee array can have fixed, adjustable, or assumed dimensions.

• A pointee cannot appear in a COMMON, DATA, EQUIVALENCE, or NAMELIST statement, and it cannot have the following attributes:

  ALLOCATABLE	OPTIONAL	SAVE
  AUTOMATIC	PARAMETER	STATIC
  INTENT	POINTER

• A pointee cannot be:

  • A dummy argument

  • A function return value

  • A record field or an array element

  • Zero-sized

  • An automatic object

  • The name of a generic interface block

• If a pointee is of derived type, it must be of sequence type.

Example

 POINTER (p, k)
 INTEGER j(2)

 ! This has the same effect as j(1) = 0, j(2) = 5
 p = LOC(j)
 k = 0
 p = p + SIZEOF(k) ! 4 for 4-byte integer
 k = 5