下表中列出了支持Objective-C語(yǔ)言的位運(yùn)算符。假設(shè)變量A=60和變量B=13,則:
運(yùn)算符 | 描述說(shuō)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 |
嘗試下面的例子就明白了所有在Objective-C編程語(yǔ)言的位運(yùn)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(dāng)編譯和執(zhí)行上述程序,它會(huì)產(chǎn)生以下結(jié)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