gcc/fortran/doc/gfortran/intrinsic-procedures/cfpointer.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. _c_f_pointer:
   7
   8 C_F_POINTER --- Convert C into Fortran pointer
   9 **********************************************
  10
  11 .. index:: C_F_POINTER, pointer, convert C to Fortran
  12
  13 .. function:: C_F_POINTER(CPTR, FPTR, SHAPE)
  14
  15   ``C_F_POINTER(CPTR, FPTR[, SHAPE])`` assigns the target of the C pointer
  16   :samp:`{CPTR}` to the Fortran pointer :samp:`{FPTR}` and specifies its shape.
  17
  18   :param CPTR:
  19     scalar of the type ``C_PTR``. It is
  20     ``INTENT(IN)``.
  21
  22   :param FPTR:
  23     pointer interoperable with :samp:`{cptr}`. It is
  24     ``INTENT(OUT)``.
  25
  26   :param SHAPE:
  27     (Optional) Rank-one array of type ``INTEGER``
  28     with ``INTENT(IN)``. It shall be present
  29     if and only if :samp:`{fptr}` is an array. The size
  30     must be equal to the rank of :samp:`{fptr}`.
  31
  32   Standard:
  33     Fortran 2003 and later
  34
  35   Class:
  36     Subroutine
  37
  38   Syntax:
  39     .. code-block:: fortran
  40
  41       CALL C_F_POINTER(CPTR, FPTR[, SHAPE])
  42
  43   Example:
  44     .. code-block:: fortran
  45
  46       program main
  47         use iso_c_binding
  48         implicit none
  49         interface
  50           subroutine my_routine(p) bind(c,name='myC_func')
  51             import :: c_ptr
  52             type(c_ptr), intent(out) :: p
  53           end subroutine
  54         end interface
  55         type(c_ptr) :: cptr
  56         real,pointer :: a(:)
  57         call my_routine(cptr)
  58         call c_f_pointer(cptr, a, [12])
  59       end program main
  60
  61   See also:
  62     :ref:`C_LOC`,
  63     :ref:`C_F_PROCPOINTER`