循环类型
| 循环类型 | 说明 |
|---|---|
| while | 当给定条件为真时，重复一个语句或一组语句。在执行循环体之前测试条件 |
| do | do语句对于将特定任务重复特定次数很有用 |
| nested（嵌套） | 可以在任何另一个while或do循环中使用一个或多个循环 |
while
while <logical expression>
<statement block>.
endwhile
report ys_sep_15.
data: a type i.
a=0.
while a<>8.
write: / 'this is the line:', a.
a=a+1.
endwhile.
This is the line: 0
This is the line: 1
This is the line: 2
This is the line: 3
This is the line: 4
This is the line: 5
This is the line: 6
This is the line: 7
DO
do [n times].
<statement block>.
enddo.
report yh_sep_15.
do 5 times.
write: / 'hello'.
enddo.
Hello
Hello
Hello
Hello
Hello
nested(嵌套)
do [n times].
<statement block n>.
do [m times].
<statement block m>.
enddo.
enddo.
report ys_sep_15.
data: a1 type i, b1 type i.
a1 = 0.
b1 = 0.
do 2 times.
a1 = a1 + 1.
write: / 'outer', a1.
do 3 times.
b1 = b1 + 1.
write: / 'inner', b1.
enddo.
enddo.
Outer 1
Inner 1
Inner 2
Inner 3
Outer 2
Inner 4
Inner 5
Inner 6
循环控制语句
| 控制语句 | 说明 |
|---|---|
| continue | 导致循环跳过其身体的剩余部分，并开始下一个循环传递 |
| check | 如果条件为假，则在check之后的剩余语句被忽略，并且系统开始下一循环通过 |
| exit | 完全终止循环，并将执行转移到循环后立即执行的语句 |
continue
report yh_sep_15.
do 5 times.
if sy-index = 3.
continue.
endif.
write / sy-index.
enddo.
1
2
4
5
check
report th_sep_15.
do 5 times.
check sy-index detween 3 and 4.
write / sy-index.
enddo.
3
4
exit
report yh_sep_15.
do 5 times.
if sy-index = 3.
exit.
endif.
write / sy-index.
enddo.
1
2
