ABAP里不用赋值操作，只用位操作实现两个整数值的交换

DATA: lv1 TYPE int4 value 30,

     lv2 TYPE int4 value 21.

FIELD-SYMBOLS: TYPE x.

ASSIGN lv1 TO CASTING.

ASSIGN lv2 TO CASTING.

= BIT-XOR .

WRITE: / lv1, lv2.