fortran goto范围 [英] fortran goto scope

问题描述

我有一个遗留的Fortran代码，带有许多像'goto 50'这样的语句。我想知道goto的目标是全球还是本地。我的意思是，如果多个函数的目标是'50'，那么goto通向哪里。

感谢您的回答。

例如，在下面的程序中，主程序和两个子程序有自己的标签50，并且gotos进入他们的行50。

  program testgotos 
 implicit none 
 
转到50 
通话第二个
通话第一个
通话第二个
 
包含
 
子程序第一个
 integer：a = 10 
 
 goto 50 
a = 20 
 50 print *，'First：a ='，a 
 
结束子程序优先
 
子程序秒
 integer :: a = 20 
 
 goto 50 
a = 40 
 50 print *，'Second：a ='，a 
 
结束子程序第二个
 
结束程序testgotos 
  

I have a legacy fortran code with many statements like 'goto 50'. I was wondering whether the target of goto is global or local. I mean, if multiple functions have a target '50', where does the goto leads to.

Thanks for answering.

解决方案

The statement labels (eg, "50") have to be defined within the current "scoping unit", which basically translates in this context to the subroutine/function that the goto call is in (or the main program, if the call is in the main program).

So for instance, in the following program, the main program and both contained subroutines have their own label 50, and the gotos go to "their" line 50.

program testgotos
    implicit none

    goto 50
    call second
 50 call first
    call second

contains

    subroutine first
    integer :: a = 10

    goto 50
    a = 20
 50 print *,'First: a = ', a

    end subroutine first

    subroutine second
    integer :: a = 20

    goto 50
    a = 40
 50 print *,'Second: a = ', a

    end subroutine second

end program testgotos

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