C++中的异或运算
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/19067286/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
XOR operation in C++
提问by Bak1139
How does the XOR logical operator work on more than two values?
XOR 逻辑运算符如何处理两个以上的值？
For instance, in an operation such as 1 ^ 3 ^ 7?
例如，在诸如 1 ^ 3 ^ 7?
0 0 0 1 // 1
0 0 1 1 // 3
0 1 1 1 // 7
__
0 1 0 1 // 5
for some reason yields 0 1 0 1, where as it should have, as I thought, yielded: 0 1 0 0, since XOR is only true when strictly one of the operands is true.
出于某种原因产生 0 1 0 1，正如我所想的那样，它应该产生：0 1 0 0，因为 XOR 仅在操作数之一严格为真时才为真。
回答by Banex
Because of the operator precedence and because the xoris a binary operator, which in this case is left-to-right.
因为运算符的优先级，并且因为xor是一个二元运算符，在这种情况下是从左到右的。
First 1 ^ 3is evaluated
首先1 ^ 3是评估
0 0 0 1 // 1
0 0 1 1 // 3
-------
0 0 1 0 // 2
The result is 2, then this number is the first operand of the last xor operation (2 ^ 7)
结果是2，那么这个数就是最后一次异或运算的第一个操作数( 2 ^ 7)
0 0 1 0 // 2
0 1 1 1 // 7
-------
0 1 0 1 // 5
The result is 5.
结果是 5。
回答by Peter G.
- XOR works bitwise, XORing each position separately
- XOR is commutative, so a^b = b^a
- XOR is associative, so (a^b)^c = a^(b^c)
- XOR 按位工作，分别对每个位置进行异或
- XOR 是可交换的，所以 a^b = b^a
- XOR 是关联的，所以 (a^b)^c = a^(b^c)
Using this, a human can count the number of ones in a given position and the result bit is set exactly for an odd number of ones in the given position of the operands.
使用它，人们可以计算给定位置中 1 的数量，并且结果位被精确设置为操作数给定位置中的奇数个 1。
Counting ones yields (0101)binary=5
计数产生 (0101)binary=5
回答by aschepler
1 ^ 3 ^ 7is not a function of three arguments, it is: (1 ^ 3) ^ 7which equals 2 ^ 7which equals 5.
1 ^ 3 ^ 7不是三个参数的函数，它是： (1 ^ 3) ^ 7which equals 2 ^ 7which equals 5。
Though actually this ^operator is associative: each bit in the result will be set if and only if an odd number of the operands had the bit set.
虽然实际上这个^运算符是关联的：当且仅当奇数个操作数设置了该位时，结果中的每个位才会被设置。
回答by Luchian Grigore
The expression is parsed as (1 ^ 3) ^ 7so you first get
表达式被解析为(1 ^ 3) ^ 7所以你首先得到
0001 ^ 0011
which is 0010. The rest is
这是0010. 剩下的就是
0010 ^ 0111
which is 0101
这是 0101
回答by john
^ is a binary operator. It doesn't work on all three numbers at once, i.e. it's (1^3)^7, which is:
^ 是一个二元运算符。它不能同时处理所有三个数字，即 (1^3)^7，即：
1 ^ 3 == 2
1 ^ 3 == 2
2 ^ 7 == 5
2 ^ 7 == 5
