fortran - 在 Fortran 中多次循环后访问派生数据类型

标签 fortran derived-types

我有以下代码:

program testdatatype

integer(8), parameter :: Stot= 2 
integer(8), dimension(Stot) :: Nf
integer(8) :: f, s, Qind
integer(8), dimension(:, :), allocatable :: NqG
real(16), dimension(:, :, :), allocatable :: d3xnormfac

type NqGtype
    integer(8), dimension(:, :), allocatable :: NqGvalT
end type NqGtype
type(NqGtype), dimension(Stot) :: NqGT

type d3xnormfactype
    real(16), dimension(:, :, :), allocatable :: d3xnormfacvalT
end type d3xnormfactype
type(d3xnormfactype), dimension(Stot) :: d3xnormfacT

! ----------------------------------------------------

! LOOP 1.1:

do s= 1, Stot, 1

    Nf(s)= 2d0

    write(*, *) 'NfLoop1.1= ', Nf(s)

end do

! LOOP 1.2:

do s= 1, Stot, 1

    write(*, *) 'NfLoop1.2= ', Nf(s)

end do

! ----------------------------------------------------

! LOOP 2.1:

do s= 1, Stot, 1

    allocate(NqG(Nf(s), Stot))

    do f= 1, Nf(s), 1

        NqG(f, s)= 5d0
        NqGT(s)%NqGvalT= NqG

        write(*, *) 'NqGLoop2.1= ', NqG(f, s)
        write(*, *) 'NqGTLoop2.1= ', NqGT(s)%NqGvalT(f, s)

    end do

    deallocate(NqG)

end do

! LOOP 2.2:

do s= 1, Stot, 1    
    do f= 1, Nf(s), 1

        write(*, *) 'NqGTLoop2.2= ', NqGT(s)%NqGvalT(f, s)

    end do
end do

! ----------------------------------------------------

! LOOP 3.1:

do s= 1, Stot, 1                    
    do f= 1, Nf(s), 1   

        allocate(d3xnormfac(Nf(s), Stot, NqGT(s)%NqGvalT(f, s)))

        do Qind= 1, NqGT(s)%NqGvalT(f, s)

            d3xnormfac(f, s, Qind)= 153d12
            d3xnormfacT(s)%d3xnormfacvalT= d3xnormfac

            write(*, *) 'd3xnormfacLoop3.1= ', d3xnormfac(f, s, Qind)
            write(*, *) 'd3xnormfacTLoop3.1= ', d3xnormfacT(s)%d3xnormfacvalT(f, s, Qind)

        end do  

        deallocate(d3xnormfac)

    end do
end do

! LOOP 3.2:

do s= 1, Stot, 1                    
    do f= 1, Nf(s), 1                       
        do Qind= 1, NqGT(s)%NqGvalT(f, s)

            write(*, *) 'd3xnormfacTLoop3.2= ', d3xnormfacT(s)%d3xnormfacvalT(f, s, Qind)

        end do
    end do
end do

! ----------------------------------------------------

end program testdatatype

我正在 mpif90 编译器上编译这个 .f90 文件。正如您所看到的，当我运行此代码时，很明显循环 1.1 中的 write 语句给出的值与循环 1.2 中的相同，即 Nf(:) 的值code> 对于循环 1.1 之外的所有 s 值都是正确的。这对于循环 2.1 和循环 2.2 是相同的(这次创建派生数据类型)。循环 1 的输出如下:

 NfLoop1.1=                     2
 NfLoop1.1=                     2
 NfLoop1.2=                     2
 NfLoop1.2=                     2

对于循环之外的任何 f 和 s 值(在循环 2.2 中)，我能够调出数据类型 NqGT(s)%NqGT(f, s) 的任何正确值，其中它被创建了(循环2.1)。目前为止没有问题。当我使用循环 2 运行循环 1 变量时，给出以下输出:

 NfLoop1.1=                     2
 NfLoop1.1=                     2
 NfLoop1.2=                     2
 NfLoop1.2=                     2
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGTLoop2.2=                     5
 NqGTLoop2.2=                     5
 NqGTLoop2.2=                     5
 NqGTLoop2.2=                     5

此外，当将循环 1 变量运行到循环 2 派生数据类型(进而与循环 3 一起使用)时，会给出以下输出:

 NfLoop1.1=                     2
 NfLoop1.1=                     2
 NfLoop1.2=                     2
 NfLoop1.2=                     2
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGLoop2.1=                     5
 NqGTLoop2.1=                     5
 NqGTLoop2.2=                     5
 NqGTLoop2.2=                     5
 NqGTLoop2.2=                     5
 NqGTLoop2.2=                     5
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.1=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=   -1.83360386755485123703987599430319601E-2466
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    0.00000000000000000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000      
 d3xnormfacTLoop3.2=    153000000000000.000000000000000000000

但是，当我尝试对 Loop 3.1 执行相同操作时，我无法再获取派生数据类型的所有正确值d3xnormfacT(s)%d3xnormfacvalT(f, s, Qind)，即循环 3.2 中打印的数据类型与循环 3.1 中相同数据类型打印的值不相等(某些值正确，但其他值不正确)。我怎样才能解决这个问题？我一定错过了一些东西(指针和/或派生数据类型的分配？)

最佳答案

在循环 3.1 中，您仅设置特定索引 d3xnormfac但然后分配整个 d3xnormfac数组到d3xnormfacT(s)%d3xnormfacvalT 。因为d3xnormfac被释放然后分配多次，之前分配的值不保证仍然被设置。

由于您的特定循环顺序，d3xnormfac(:,1,:) 中的值未初始化。取决于编译器是否重新分配 d3xnormfac到同一个地方并且内存是否被清理，这些值最终可能是正确的。对于我的 Intel(使用 -assume realloc-lhs 以允许自动分配)，大多数值都是正确的。对于我的 gfortran，大多数值都是不正确的，如您所见。该行为可能也取决于真实的类型，这解释了您的观察结果。

了解这一点的一个好方法是在分配后初始化每个值。修改代码以将其添加到循环 3.1 中:

        allocate(d3xnormfac(Nf(s), Stot, NqGT(s)%NqGvalT(f, s)))
        d3xnormfac = -1234     ! -- Added this line

        do Qind= 1, NqGT(s)%NqGvalT(f, s)

产生以下结果:

mach5% ifort -assume realloc_lhs -check all -warn all -traceback -g main.f90 && ./a.out 
 NfIN=                      2
 NfIN=                      2
 NfOUT=                      2
 NfOUT=                      2
 NqGIN=                     15
 NqGTIN=                     15
 NqGIN=                     15
 NqGTIN=                     15
 NqGIN=                     15
 NqGTIN=                     15
 NqGIN=                     15
 NqGTIN=                     15
 NqGTOUT=                     15
 NqGTOUT=                     15
 NqGTOUT=                     15
 NqGTOUT=                     15
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacIN=    153000000000000.000000000000000000      
 d3xnormfacTIN=    153000000000000.000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=   -1234.00000000000000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000      
 d3xnormfacTOUT=    153000000000000.000000000000000000

您可以看到仍设置为 -1234 的部分。

澄清后

我现在发现这个问题来自于对可分配数组如何属于派生类型的误解。 d3xnormfacT(s)%d3xnormfacvalT是它自己的可分配数组。它的排名为 3，并且(在分配之前)未分配。它(通常)使用常规分配语句进行分配，例如:

allocate(d3xnormfacT(s)%d3xnormfacvalT((Nf(s), Stot, NqGT(s)%NqGvalT(f, s)))

你没有这样做。您(无意中)使用 Fortran 的高级功能绕过了传统分配:自动左侧 (lhs) 分配。当为数组分配一个与其形状匹配的值时，该数组将被分配或重新分配以匹配。更多信息在这里:Automatic array allocation upon assignment in Fortran

您的声明:

        d3xnormfacT(s)%d3xnormfacvalT= d3xnormfac

实际上是同时做两件事。第一，d3xnormfacT(s)%d3xnormfacvalT正在分配以匹配 d3xnormfac 的大小，因为d3xnormfacT(s)%d3xnormfacvalT与 d3xnormfac 的形状(3 维)匹配。二、新分配d3xnormfacT(s)%d3xnormfacvalT被分配与 d3xnormfac 相同的值有。 (没有人指出其他任何事情。)

您应该更改代码以不使用此自动 lhs 分配。 2003 年标准允许这种自动 lhs 分配，但某些编译器(Intel 直到 2017 年)故意默认不支持它。我个人认为这是危险且不直观的，所以我通常会避免它。对于不了解此功能的开发人员来说，此功能可能是一个“陷阱”。防止这种情况发生的 gfortran (我猜你正在使用它，你只指定 mpif90 这只是一个包装器)标志是 -fno-realloc-lhs .

一旦您更改了代码，您将更好地理解我的答案的其余部分，这就是您看到问题的真正原因。

编辑:正如 @eriktous 指出的那样，循环 2 中也存在同样的问题，但循环顺序意味着不会将未初始化的值放入输出中。我不太明白为什么s 索引派生数据类型和数组的最外层维度。也许是因为这只是一个玩具盒。如果您要扩展此代码，请务必解决这两个问题。

关于fortran - 在 Fortran 中多次循环后访问派生数据类型，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48508876/

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