Question

我想在ABAP中编写Hanoi塔求解器。

这是我当前的代码：

FORM SOLVE USING s1 TYPE c
             s2 TYPE c
             s3 TYPE c
             n  TYPE i.

  IF n = 1.

    "move disc from tower X to tower Y"
    WRITE:/ text-001, text-002, s1, text-003, text-002, s3.

  ELSE.

    PERFORM solve USING s1 s3 s2 n-1. "Here's my problem, n-1 doesn't work"

    PERFORM solve USING s1 s2 s3 1.

    PERFORM solve USING s2 s1 s3 n-1.

  ENDIF.

ENDFORM.

我的问题：

如果我选择了USING之类的n-1参数，SAP会将其识别为（不存在的）结构，并向我抛出错误。

反正有办法做到吗？

非常感谢。

Answer 1

您需要在运算符之间添加空格。因此，您需要输入n - 1。另一方面，旧版本的ABAP不支持将内联操作数用作函数/执行参数。如果遇到错误，请首先将结果分配给新变量，然后将其作为参数传递。

Answer 2

这是我的解决方案。效果很好。感谢您提供的有用提示。

*&---------------------------------------------------------------------*
*& Report  ZS_SANDBOX_TOH
*&
*&---------------------------------------------------------------------*
*& 
*& Datum: 19.09.2018
*& Beschreibung: Lösungsprogramm für das Türme von Hanoi - Problem
*&---------------------------------------------------------------------*

REPORT ZS_SANDBOX_TOH.

PARAMETERS: p_discs TYPE i.

CLASS myclass DEFINITION.

  PUBLIC SECTION.

    CLASS-METHODS solve IMPORTING s1 TYPE c
                                  s2 TYPE c
                                  s3 TYPE c
                                  n1 TYPE i.

ENDCLASS.

CLASS myclass IMPLEMENTATION.

METHOD solve.

  IF n1 = 1.

    WRITE:/ 'Lege Scheibe von Turm ', s1, ' auf Turm ', s3.

  ELSE.

    solve( s1 = s1
           s2 = s3
           s3 = s2
           n1 = n1 - 1 ).

    solve( s1 = s1
           s2 = s2
           s3 = s3
           n1 = 1 ).

    solve( s1 = s2
           s2 = s1
           s3 = s3
           n1 = n1 - 1 ).

  ENDIF.

ENDMETHOD.

ENDCLASS.

START-OF-SELECTION.

CALL METHOD myclass=>solve( s1 = 'A'
                            s2 = 'B'
                            s3 = 'C'
                            n1 = p_discs ).

子例程调用的参数“ n-1”给出语法错误

2 个答案: