if-statement - 将 Go-to 语句从 FORTRAN 77 转换为 Fortran 90

Question

I am working on a piece of legacy F77 code and trying to convert it to equivalent F90 code. I ran into these lines below and could some one advise if my conversion is correct?

Fortran 77 代码:

Subroutine area(x,y,z,d)
do 15 j=1,10
if (a.gt.b) go to 20
15 CONTINUE
20 Statement 1
   Statement 2
   Statement 3
end subroutine

我尝试将其转换为 F90，结果如下:

Subroutine area(x,y,z,d)
  dloop: do j=1,10
    if (a>b) then 
      statement 1
      statement 2
      statement 3
    else
      write(*,*) 'Exiting dloop'
      exit dloop
    end if
  end do dloop
end subroutine

谁能告诉我这种方法是否正确？在我的结果中，我没有得到我期望的结果。所以我的逻辑可能有问题。

Answer 1

你的翻译有点错误...第一步是重建 do 循环，它在 15 处循环:

Subroutine area(x,y,z,d)
do j=1,10
  if (a.gt.b) go to 20
enddo
20 Statement 1
   Statement 2
   Statement 3
end subroutine

现在您可以看到 goto 导致“跳出循环”。在这个特定的例子中，这相当于一个exit，代码可以写成

Subroutine area(x,y,z,d)
  do j=1,10
    if (a.gt.b) exit
  enddo
  Statement 1
  Statement 2
  Statement 3
end subroutine