通用块和子例程参数

问题描述

如果在名为myCB的公共块中有一个名为var的变量，我可以使用相同的名称在其他两个不使用公共块myCB的子例程之间传递参数吗?

If I have a variable called var which is in a common block named myCB may I use the same name to pass an argument between two other subroutines which are not using the common block myCB?

代码如下.

Subroutine SR1(Var)
      !something here using Var
end Subroutine SR1

Subroutine SR2()
....
      Call SR1(B)
....
end Subroutine SR2

Subroutine SR3()
common \myCB\ Var
...
  ! something using the other Var shared with SR4
......
end Subroutine SR3

Subroutine SR4()
common \myCB\ Var
....
... ! something using the other Var shared with SR3
....
end Subroutine SR4

我确实在SR1和SR2之间传递Var时遇到问题，问题可能出在公共块中的另一个名为Var的问题上吗?

I do have problem with Var passing between SR1 and SR2, could the problem come from the other named Var in the common block ?

推荐答案

如果您不想过多地修改旧代码库，建议您将common块放在module中，然后导入变量需要访问权限时:

If you don't want to modify the legacy code base too much, I suggest you put the common block in a module and import the variables when access is required:

module myCB_mod
    common /myCB/ var, var2, var3
    save ! This is not necessary in Fortran 2008+
end module myCB_mod

subroutine SR2()
    use myCB_mod
    !.......
    call SR1(B)
    !.....
end subroutine SR2

subroutine SR3()
    use myCB_mod
    !.......
end subroutine SR3

subroutine SR4()
    use myCB_mod
    !.....
end subroutine SR4

或更妙的是，我建议您完全避免使用common块(这需要完全重写旧代码库)，并将所有子例程限制在module

or better yet, I suggest you avoid common blocks altogether (this requires a full rewrite of the legacy code base) and confine all your subroutines inside a module

module myCB
    implicit none
    real var, var2, var3
    save ! This is not necessary in Fortran 2008+
end module myCB

module mySubs
    use myCB
    implicit none
contains
    subroutine SR2()
            !.......
            call SR1(B)
            !.....
    end subroutine SR2

    subroutine SR3()
            !.......
    end subroutine SR3

    subroutine SR4()
            !.....
    end subroutine SR4
end module

最后，common块中的变量是否需要初始化?如果是这样，这甚至会导致涉及data语句甚至block data构造的更多复杂情况.

Lastly, do the variables in your common block require initialization? If so, this introduces even further complications involving data statements or even the block data construct.

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