不用中間變量進行兩個int值的交換

1. Oracle PL/SQL的實現

declare a number := 123; b number := 435; begin dbms_output.put_line('交換前'); dbms_output.put_line('a = ' || a); dbms_output.put_line('b = ' || b); a := a + b; b := a - b; a := a - b; dbms_output.put_line('交換後'); dbms_output.put_line('a = ' || a); dbms_output.put_line('b = ' || b); end;

 

結果：

-------------------------

交換前
a = 123
b = 435
交換後
a = 435
b = 123

-------------------------

 

2. 使用位運算，如Java

 

int a = 501; int b = 126; System.out.println(a); System.out.println(b); a ^= b; b ^= a; a ^= b; System.out.println(a); System.out.println(b);

 

結果：

501
126
126
501

 

3. 補充一下Oracle關於位運算

declare a number := 123; b number := 435; begin dbms_output.put_line('交換前'); dbms_output.put_line('a = ' || a); dbms_output.put_line('b = ' || b); a := to_number(UTL_RAW.BIT_XOR(to_char(a), to_char(b))); b := to_number(UTL_RAW.BIT_XOR(to_char(a), to_char(b))); a := to_number(UTL_RAW.BIT_XOR(to_char(a), to_char(b))); /* a := a + b; b := a - b; a := a - b; */ dbms_output.put_line('交換後'); dbms_output.put_line('a = ' || a); dbms_output.put_line('b = ' || b); end;

 

結果：

-------------------------

交換前
a = 123
b = 435
交換後
a = 435
b = 123

-------------------------