fortran - 在fortran中使用数组成员作为do循环的控制变量

Question

我很惊讶您不能像这样将数组成员作为 do 循环的控制变量:

program test
    integer, dimension(2) :: i 

    do i(1) = 1, 3
    do i(2) = 1, 3
        ! anything here
        write(*, *) i
    end do
    end do
end program

我的问题是为什么不允许这样做？

编辑:
还是允许但我做错了？

ifort v 11.1 的错误消息是:

test.f90(4): error #5082: Syntax error, found IDENTIFIER 'I' when expecting one of: ( % : . = =>
    do i(1) = 1, 3
-------^
test.f90(4): error #5082: Syntax error, found ',' when expecting one of: <END-OF-STATEMENT> ;
    do i(1) = 1, 3
---------------^
test.f90(5): error #5082: Syntax error, found IDENTIFIER 'I' when expecting one of: ( % : . = =>
    do i(2) = 1, 3
-------^
test.f90(5): error #5082: Syntax error, found ',' when expecting one of: <END-OF-STATEMENT> ;
    do i(2) = 1, 3
---------------^
test.f90(4): error #6535: This variable or component must be of a derived or structure type   [DO]
    do i(1) = 1, 3
----^
test.f90(4): error #6460: This is not a field name that is defined in the encompassing structure.   [I]
    do i(1) = 1, 3
-------^
test.f90(8): error #6099: An ENDDO statement occurred without a corresponding DO or DO WHILE statement.
    end do
----^
test.f90(9): error #6099: An ENDDO statement occurred without a corresponding DO or DO WHILE statement.
    end do
----^

来自 gfortran V4.5.1 & 4.8.3 的错误信息是:

test.f90:4.4:

    do i(1) = 1, 3
    1
Error: Unclassifiable statement at (1)
test.f90:5.4:

    do i(2) = 1, 3
    1
Error: Unclassifiable statement at (1)
test.f90:8.7:

    end do
       1
Error: Expecting END PROGRAM statement at (1)
test.f90:9.7:

    end do
       1
Error: Expecting END PROGRAM statement at (1)

Answer 1

对不起，我的第一个错误答案。

该限制遵循语言规则:

Fortran 2008 (ISO/IEC 1539-1:2010) 8.1.6.2:

R818 loop-control is, do-variable = ...

R819 do-variable is, scalar-int-variable-name

C812 (R819) The do-variable shall be a variable of type integer.

因此，是的，在循环控制变量的位置只允许使用标量变量名称。

如果你问为什么语言的规则是这样的，你必须问标准的作者，SC22/WG5 和 X3J3，但我猜这与固定源形式的句法无歧义的必要性有关。在固定源格式中，空格并不重要，很难提出明确的语法。