--IF語句：
1.判斷語法.
IF<condition_1>.
<Statements...>.
ENDIF.
-- 例子:
Data Title_1(20) TYPE C.
Title_1 = 'Tutorials'.
IF Title_1 = 'Tutorials'.
write 'This is IF statement'.
ENDIF.
--IF ELSE語法：
IF<condition_1>.
<statement block 1>.
ELSE.
<statement block 2>.
ENDIF.
--例子:
Data Title_1(20) TYPE C.
Title_1 = 'Tutorials'.
IF Title_1 = 'Tutorial'.
write 'This is IF Statement'.
ELSE.
write 'This is ELSE Statement'.
ENDIF.
--復雜IF ELSEIF語法:
IF<condition_1>.
<statement block 1>.
ELSEIF<condition_2>.
<statement block 2>.
ELSEIF<condition_3>.
<statement block 3>.
......
......
......
......
ELSE.
<statement block>.
ENDIF.
--例子:
Data Result TYPE I VALUE 65.
IF Result < 0.
Write / 'Result is less than zero'.
ELSEIF Result < 70.
Write / 'Result is less than seventy'.
ELSE.
Write / 'Result is greater than seventy'.
ENDIF.
--Case語法：
CASE <field>.
WHEN <abc>.
<statement block>.
WHEN <def>.
<tatement block>.
WHEN <pqr>.
<statement block>.
......
......
......
WHEN <xyz>.
<statement block>.
WHEN OTHERS.
<statement block>.
ENDCASE.
--例子
Data: Title_1(10) TYPE C,
Title_2(15) TYPE C.
Title_1 = 'ABAP'.
Title_2 = 'Programming'.
CASE Title_2.
WHEN 'ABAP'.
Write 'This is not the title'.
WHEN 'Tutorials'.
Write 'This is not the title'.
WHEN 'Limited'.
Write 'This is not the title'.
WHEN 'Programming'.
Write 'Yes, this is the title'.
WHEN OTHERS.
Write 'Sorry, Mismatch'.
ENDCASE.
循環LOOP,簡單來講只有兩種循環：
a.按循環次數執行，執行n次：DO
DO [n TIMES].
<statement block>.
ENDDO.
--例子:循環15次：
Do 15 TIMES.
Write: / 'Hello'.
ENDDO.
b.WHILE循環: 執行到符合條件處跳出
WHILE <logical expression>
<statement block>.
ENDWHILE.
--例子：
DATA: a type i.
a = 0.
WHILE a <> 8.
Write: / 'This is the line:', a.
a = a + 1.
ENDWHILE.
--CHECK,是在循環中使用,當表達為true則執行之后語句,否則不執行並馬繼續下一個循環.
DO 5 TIMES.
CHECK SY-INDEX BETWEEN 3 AND 4.
Write / SY-INDEX.
ENDDO.
--CONTINUE,與其它語言一樣. 跳出本層循環的當次循環，進入本層的下次循環.
DO 5 TIMES.
IF SY-INDEX = 3.
CONTINUE.
ENDIF.
Write / SY-INDEX.
ENDDO.
--EXIT,與其它語言一樣. 跳出當前循環
DO 5 TIMES.
IF SY-INDEX = 3.
EXIT.
ENDIF.
Write / SY-INDEX.
ENDDO.
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版權聲明：本文為CSDN博主「vikingwei2015」的原創文章
原文鏈接：https://blog.csdn.net/vikingwei2015/article/details/84924756