loop循环时须注意效率问题

以前写循环时，都是一条记录一条记录的比较，代码示例如下：

loop at S_VAL_CHAR into VAL_CHAR.
    if VAL_CHAR-CHARACT eq 'P0008_7'."箱型
        IT_ITEM-BOX = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'S0012'."客户编号
        IT_ITEM-CLIENT_CODE = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'CP_CW'."客户编号
        IT_ITEM-CP_CW = VAL_CHAR-VALUE_CHAR.
    ENDIF.
ENDLOOP.

这样的话要循环lines(  S_VAL_CHAR ).

应该改成如下，效率应该会好一点.

loop at S_VAL_CHAR into VAL_CHAR WHERE CHARACT eq 'P0008_7' OR CHARACT eq 'S0012' OR CHARACT eq 'CP_CW'.
    if VAL_CHAR-CHARACT eq 'P0008_7'."箱型
        IT_ITEM-BOX = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'S0012'."客户编号
        IT_ITEM-CLIENT_CODE = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'CP_CW'."客户编号
        IT_ITEM-CP_CW = VAL_CHAR-VALUE_CHAR.
    ENDIF.
ENDLOOP.

 若条件很多，条件语句写起来太长，可用range，代码如下：

data:lr_character type range of BAPI1003_ALLOC_VALUES_CHAR-CHARACT,
lr_character_line like line of lr_character.
CLEAR: lr_character_line,lr_character[].
lr_character_line = 'IEQ'.
lr_character_line-low = 'P0008_7'.
append lr_character_line to lr_character.

CLEAR: lr_character_line.
lr_character_line = 'IEQ'.
lr_character_line-low = 'S0012'.
append lr_character_line to lr_character.

CLEAR: lr_character_line.
lr_character_line = 'IEQ'.
lr_character_line-low = 'CP_CW'.
append lr_character_line to lr_character.

loop at S_VAL_CHAR into VAL_CHAR WHERE CHARACT in lr_character.
    if VAL_CHAR-CHARACT eq 'P0008_7'."箱型
        IT_ITEM-BOX = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'S0012'."客户编号
        IT_ITEM-CLIENT_CODE = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'CP_CW'."客户编号
        IT_ITEM-CP_CW = VAL_CHAR-VALUE_CHAR.
    ENDIF.
ENDLOOP.

继续优化一下，把那些重复的代码提取出来，最后如下：

data:    lr_character type range of BAPI1003_ALLOC_VALUES_CHAR-CHARACT,
            lr_character_line like line of lr_character.
            
form ADD_CHARACTER_TO_RANGE USING value(s) CHANGING r.
    clear lr_character_line.
    lr_character_line = 'IEQ'.
    lr_character_line-low = s.
    append lr_character_line to lr_character.
ENDFORM.

CLEAR: lr_character[].
perform ADD_CHARACTER_TO_RANGE using 'P0008_7' changing lr_character.
perform ADD_CHARACTER_TO_RANGE using 'S0012' changing lr_character.
perform ADD_CHARACTER_TO_RANGE using 'CP_CW' changing lr_character.

loop at S_VAL_CHAR into VAL_CHAR WHERE CHARACT in lr_character.
    if VAL_CHAR-CHARACT eq 'P0008_7'."箱型
        IT_ITEM-BOX = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'S0012'."客户编号
        IT_ITEM-CLIENT_CODE = VAL_CHAR-VALUE_CHAR.
    ELSEIF VAL_CHAR-CHARACT eq 'CP_CW'."客户编号
        IT_ITEM-CP_CW = VAL_CHAR-VALUE_CHAR.
    ENDIF.
ENDLOOP.