ABAP/4 ОКМ ДМ экономическая информатика 4GL Теория и практика обработки информации

Компьютерный язык ABAP/4 - ключевые слова

CASE

Basic form

CASE f.
Effect Case distinction.

Depending on the current contents of a field, this statement executes one of several alternative processing branches. The field whose contents determine how the subsequent processing is specified after CASE ; the individual processing branches are introduced by WHEN , followed by the value to be tested. The entire block is concluded by ENDCASE . The structure of the CASE statement is as follows:


CASE f.
  WHEN f1.
    ...
  WHEN f2.
    ...
  ...
ENDCASE.

On reaching such a CASE statement, the processor compares f with f1 .
If f = f1 , it executes the processing block between " WHEN f1. " and the next WHEN statement. If there are no further WHEN statements, it executes the processing block up to the ENDCASE statement and then continues with any subsequent processing.
If f <> f1 , the processor compares the field f2 in the next WHEN statement with f and proceeds as with f1 and so on.

Although f should be a variable, f1 can be a variable or a literal. For the comparison " f = f1 ", the rules are the same as for IF .

There is a second variant of the WHEN statement:

WHEN OTHERS.
No more than one such WHEN statement is allowed within a CASE block. The " WHEN OTHERS " processing block is always concluded by ENDCASE , i.e. no further WHEN statements can follow.

The " WHEN OTHERS " processing block is executed only if none of the preceding WHEN blocks have been executed, i.e. if all previous comparisons (" f = ... ) have returned a negative result.

Example


DATA: ONE   TYPE I VALUE 1,
      THREE TYPE P VALUE 3.
DO 5 TIMES.
  CASE SY-INDEX.
    WHEN ONE.
      WRITE / 'That is'.
    WHEN 2.
      WRITE   'a'.
    WHEN THREE.
      WRITE 'good'.
      WRITE 'example'.
    WHEN OTHERS.
      WRITE '!'.
  ENDCASE.
ENDDO.

Output: " That is a good example ! ! "

Notes

You can nest several CASE statements and even combine them with IF statements.
The statement " WHEN: f1, f2. " does not make sense. The example below shows that the block belonging to " WHEN f1 " is empty:

WHEN f1.
WHEN f2.
Related IF , ELSEIF

Index
© SAP AG 1996

ABAP/4 ОКМ ДМ экономическая информатика 4GL Теория и практика обработки информации

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