Objective-C 位運算符

下表中列出了支持Objective-C語言的位運算符。假設變量A=60和變量B=13，則：

運算符

描述說明

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

嘗試下面的例子就明白了所有在Objective-C編程語言的位運算符：

#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 ); }

當編譯和執行上述程序，它會產生以下結果：

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