Fortran 90 使用描述符来表示其数组的维度(形状)并传递假定形状的数组参数。 Fortran 中的指针也很特殊——它们只能指向合格的目标。与 C/C++ 相比,Fortran 中的调试器自省效果要好得多。只需使用print arr(index)
或其中之一info
命令——不需要花哨的东西。
示例代码:
program arr
real, dimension(40) :: stack_array
real, allocatable, dimension(:), target :: heap_array
real, dimension(:), pointer :: ptr_array
integer :: i
! Interface required because of the assumed-shape array argument
interface
subroutine foo(bar, baz, qux, ptr)
real, dimension(:) :: bar
real, dimension(40) :: baz
real, dimension(*) :: qux
real, dimension(:), pointer :: ptr
end subroutine foo
end interface
allocate(heap_array(40))
forall(i = 1:40) stack_array(i) = i
heap_array = stack_array + 2
ptr_array => heap_array
print *, stack_array(1)
call foo(stack_array, stack_array, stack_array, ptr_array)
deallocate(heap_array)
end program arr
subroutine foo(bar, baz, qux, ptr)
real, dimension(:) :: bar
real, dimension(40) :: baz
real, dimension(*) :: qux
real, dimension(:), pointer :: ptr
print *, bar(1), baz(1), qux(1), ptr(1)
end subroutine foo
使用调试信息进行编译并运行gdb
:
$ gfortran -g -o arr.x arr.f90 && gdb ./arr.x
...
(gdb) info locals
heap_array = (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ...
ptr_array = (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ...
stack_array = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...
(gdb) print heap_array
$1 = (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, ...
(gdb) print ptr_array(3:7)
$2 = (5, 6, 7, 8, 9)
...
(gdb) info args
bar = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ...
baz = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, ...
qux = ()
ptr = (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, ...
由于明显的原因,它无法显示假定大小的数组参数的内容,但您可以单独打印每个元素:
(gdb) print qux(1)
$5 = 1
(gdb) print qux(2)
$6 = 2
(gdb) print qux(15)
$7 = 15
请注意,打印数组部分不适用于假定大小的数组参数,因为它们不是由描述符传递的,并且gdb
遇到麻烦:
(gdb) print qux(1:8)
$8 = (0, 0, 0, 0, 0, 0, 2.25609053e-43, 0)
(gdb) print qux(2:9)
$9 = (0, 0, 0, 0, 0, 0, 2.25609053e-43, 0)