& – Bitwise AND 按位与，都为真才为真 | – Bitwise OR 按位或，只要有一个为真就为真 ~ – One’s complement 取反 ^ – Bitwise XOR 按位异或，只有一个为假时为真 << – left shift 左移 大多数情况下可以理解为左移a位就是乘以2^a >> – right shift 左移 大多数情况下可以理解为右移a位就是除以2^a
这6种运算符中，除了取反~运算符外，其它的都是二目运算符，就是要求运算符两侧各有一个运算量，运算量是整型或者字符型的数据
位运算能干的还挺多，比如swap功能(数值交换)，奇偶性判断，左移右移在计算oracle rdba时更方便
#include <stdio.h>
void main()
{
int a=12,b=14;
a^=b;
b^=a;
a^=b;
printf("A=%d,B=%d\n",a,b);
printf("Average is %d\n",(a+b)>>1);
if((a&1)==1)
{
printf("A is odd\n");
}
else
{
printf("A is even\n");
}
printf("The int range is %d\n",(1<<31)-1);
int rdba=0xff4062ff;
int file=0x3FF&(rdba>>22);
int block=rdba&0x3FFFFF;
printf("File=%d,Block=%d\n",file,block);
}
Oracle的bitand函数
SQL> select bitand(6,3) from dual;
BITAND(6,3)
-----------
2
SQL> select bitand(
bin_to_num(1,1,0),
bin_to_num(0,1,1)) value
from dual; 2 3 4
VALUE
----------
2
SQL>
以下引自orafaq
oracle's bitand (most sql implementations use the & operator):
sql> select bitand(2, 4) from dual;
bitand(2,4)
-----------
0
A.to simulate bitor (most sql implementations use the | operator):
create function bitor(x in number, y in number) return number as
begin
return x + y - bitand(x,y);
end;
/
sql> select bitor(2, 4) from dual;
bitor(2,4)
----------
6
B.to simulate bitxor (most sql implementations use the ^ operator):
create function bitxor(x in number, y in number) return number as
begin
return bitor(x,y) - bitand(x,y);
end;
/
sql> select bitxor(2, 4) from dual;
bitxor(2,4)
-----------
6
C.to simulate bitnot (most sql implementations use the ~ operator):
create function bitnot(x in number) return number as
begin
return (0 - x) - 1;
end;
/
其实utl_raw也包含类似的函数
SQL> desc utl_raw
FUNCTION BIT_AND RETURNS RAW Argument Name Type In/Out Default? ------------------------------ ----------------------- ------ -------- R1 RAW IN R2 RAW IN FUNCTION BIT_COMPLEMENT RETURNS RAW Argument Name Type In/Out Default? ------------------------------ ----------------------- ------ -------- R RAW IN FUNCTION BIT_OR RETURNS RAW Argument Name Type In/Out Default? ------------------------------ ----------------------- ------ -------- R1 RAW IN R2 RAW IN FUNCTION BIT_XOR RETURNS RAW Argument Name Type In/Out Default? ------------------------------ ----------------------- ------ -------- R1 RAW IN R2 RAW IN
Reference
http://www.orafaq.com/wiki/Bit
http://www.thegeekstuff.com/2012/10/bitwise-operators/
