C_ASSOCIATED - The GNU Fortran Compiler
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### 8.39 `C_ASSOCIATED` — Status of a C pointer

Description:
  `C_ASSOCIATED(c_prt_1[, c_ptr_2])` determines the status of the C pointer c_ptr_1 or if c_ptr_1 is associated with the target c_ptr_2.
Standard:
  Fortran 2003 and later
Class:
  Inquiry function
Syntax:
  `RESULT = C_ASSOCIATED(c_prt_1[, c_ptr_2])`
Arguments:

  c_ptr_1 | Scalar of the type `C_PTR` or `C_FUNPTR`.
  c_ptr_2 | (Optional) Scalar of the same type as c_ptr_1.

Return value:
  The return value is of type `LOGICAL`; it is `.false.` if either c_ptr_1 is a C NULL pointer or if c_ptr1 and c_ptr_2 point to different addresses.
Example:

                subroutine association_test(a,b)
                  use iso_c_binding, only: c_associated, c_loc, c_ptr
                  implicit none
                  real, pointer :: a
                  type(c_ptr) :: b
                  if(c_associated(b, c_loc(a))) &
                     stop 'b and a do not point to same target'
                end subroutine association_test

See also:
  C_LOC, C_FUNLOC