8.76 MALLOC — Allocate dynamic memory

Description:

MALLOC(SIZE) allocates SIZE bytes of dynamic memory and returns the address of the allocated memory. The MALLOC intrinsic is an extension intended to be used with Cray pointers, and is provided in gfortran to allow user to compile legacy code. For new code using Fortran 95 pointers, the memory allocation intrinsic is ALLOCATE.

Option:

gnu

Class:

non-elemental function

Syntax:

PTR = MALLOC(SIZE)

Arguments:

SIZE	The type shall be INTEGER(*).

Return value:

The return value is of type INTEGER(K), with K such that variables of type INTEGER(K) have the same size as C pointers (sizeof(void *)).

Example:

The following example demonstrates the use of MALLOC and FREE with Cray pointers. This example is intended to run on 32-bit systems, where the default integer kind is suitable to store pointers; on 64-bit systems, ptr_x would need to be declared as integer(kind=8).

          program test_malloc
            integer i
            integer ptr_x
            real*8 x(*), z
            pointer(ptr_x,x)
          
            ptr_x = malloc(20*8)
            do i = 1, 20
              x(i) = sqrt(1.0d0 / i)
            end do
            z = 0
            do i = 1, 20
              z = z + x(i)
              print *, z
            end do
            call free(ptr_x)
          end program test_malloc