Objective-C 位运算符

转自：http://www.yiibai.com/objective_c/objective_c_bitwise_operators.html

下表中列出了支持Objective-C语言的位运算符。假设变量A=60和变量B=13，则：

运算符	描述说明	示例
&	Binary AND Operator copies a bit to the result if it exists in both operands.	(A & B) will give 12, which is 0000 1100
|	Binary OR Operator copies a bit if it exists in either operand.	(A | B) will give 61, which is 0011 1101
^	Binary XOR Operator copies the bit if it is set in one operand but not both.	(A ^ B) will give 49, which is 0011 0001
~	Binary Ones Complement Operator is unary and has the effect of 'flipping' bits.	(~A ) will give -61, which is 1100 0011 in 2's complement form due to a signed binary number.
<<	Binary Left Shift Operator. The left operand's value is moved left by the number of bits specified by the right operand.	A << 2 will give 240, which is 1111 0000
>>	Binary Right Shift Operator. The left operand's value is moved right by the number of bits specified by the right operand.	A >> 2 will give 15, which is 0000 1111

例子

尝试下面的例子就明白了所有在Objective-C编程语言的位运算符：

#import <Foundation/Foundation.h>

main()
{

   unsigned int a = 60;	/* 60 = 0011 1100 */  
   unsigned int b = 13;	/* 13 = 0000 1101 */
   int c = 0;           

   c = a & b;       /* 12 = 0000 1100 */ 
   NSLog(@"Line 1 - Value of c is %d
", c );

   c = a | b;       /* 61 = 0011 1101 */
   NSLog(@"Line 2 - Value of c is %d
", c );

   c = a ^ b;       /* 49 = 0011 0001 */
   NSLog(@"Line 3 - Value of c is %d
", c );

   c = ~a;          /*-61 = 1100 0011 */
   NSLog(@"Line 4 - Value of c is %d
", c );

   c = a << 2;     /* 240 = 1111 0000 */
   NSLog(@"Line 5 - Value of c is %d
", c );

   c = a >> 2;     /* 15 = 0000 1111 */
   NSLog(@"Line 6 - Value of c is %d
", c );
}

当编译和执行上述程序，它会产生以下结果：

2013-09-07 22:11:51.652 demo[30836] Line 1 - Value of c is 12
2013-09-07 22:11:51.652 demo[30836] Line 2 - Value of c is 61
2013-09-07 22:11:51.652 demo[30836] Line 3 - Value of c is 49
2013-09-07 22:11:51.652 demo[30836] Line 4 - Value of c is -61
2013-09-07 22:11:51.652 demo[30836] Line 5 - Value of c is 240
2013-09-07 22:11:51.652 demo[30836] Line 6 - Value of c is 15