数组指针参数在返回时为什么改变了指向的数据？

li913

1、运行会报错，等号下面的不能输出，角标越界。
2、fortran的指针只能作为一个整体去执行“指向”操作，data_2d(i:i, 1:ncol) => data_1d(1+(i-1)*ncol : (i-1)*ncol+ncol) 这一句的意思是 data_2d的第一个角标上下限都是i，第二个角标1:到4 。重复3次后，最终相当于data_2d(3:3,1:4)这样一个数组。因此第二次输出会导致越界。

[Fortran] 纯文本查看 复制代码

SUBROUTINE BIANXING(data_2d, data_1d, nrow, ncol)
    implicit none
    REAL, DIMENSION(:,:), POINTER, INTENT(INOUT) :: data_2d
    REAL, DIMENSION(:), POINTER, INTENT(IN) :: data_1d
    INTEGER, INTENT(IN) :: nrow
    INTEGER, INTENT(IN) :: ncol

    data_2d(1:ncol,1:nrow) => data_1d
    write(*,"(4f6.1)") data_2d
END SUBROUTINE BIANXING


PROGRAM MAIN
    implicit none
    INTERFACE
SUBROUTINE BIANXING(data_2d, data_1d, nrow, ncol)
    implicit none
    REAL, DIMENSION(:,:), POINTER, INTENT(INOUT) :: data_2d
    REAL, DIMENSION(:), POINTER, INTENT(IN) :: data_1d
    INTEGER, INTENT(IN) :: nrow
    INTEGER, INTENT(IN) :: ncol
END SUBROUTINE BIANXING
    END INTERFACE

    REAL, DIMENSION(12), TARGET :: arr
    REAL, DIMENSION(:), POINTER :: p_1d
    REAL, DIMENSION(:, :), POINTER :: p_2d
    INTEGER :: i
    arr = (/1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12/)
    p_1d => arr
    
    call BIANXING(p_2d, p_1d, 3, 4)

    PRINT *, "===================================="
    write(*,"(4f6.1)")  p_2d

END PROGRAM MAIN