Javascript 波浪号和二进制补码
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Javascript Tilde & Two's complement
提问by Royi Namir
Two's complement method- generates -(x + 1).
二进制补码方法- 生成-(x + 1).
for example when JavaScript encounters the Tilde he uses this method:
例如，当 JavaScript 遇到波浪号时，他会使用以下方法：
~5 = -(5+1) = -6.
Fine - lets go deeper.
很好 - 让我们更深入。
Now lets talk about the Two's complement method.
现在让我们谈谈二进制补码方法。
5 = 0000 0101
Flip = 1111 1010
add one = 1111 1011
so 1111 1011is -5.
所以1111 1011是-5。
how ?
如何 ？
again : flip :
再次：翻转：
0000 0100
add one :
添加一个：
0000 0101
And so it was -5.
原来如此-5。
So how does this settle with ~5=-6?
那么这是如何解决的 ~5=-6呢？
where this -6came from ?
这-6是从哪里来的？
回答by Aleksander Blomsk?ld
First of all, you need to realize that ~is the bitwise flip operator, which is not the same as the negate operator -. ~does only do the bitwise flipping, but the negate operator -does bitwise flipping and add one (for integers).
首先，您需要意识到它~是按位翻转运算符，它与否定运算符不同-。~只执行按位翻转，但否定运算符-执行按位翻转并加一（对于整数）。
As you've explained, if yo want to go from a postive number nto -nusing the two complement method you bitwise flip/not n and add 1. ~n is just the bit-wise not meaning that ~n=-n-1.
正如你所解释的，如果你想从一个正数n到-n使用两个补码方法你按位翻转/不是 n 并加 1。 ~n 只是按位而不意味着~n=-n-1.
For instance:
例如：
5 = 0000 0101
Flipped (~5) = 1111 1010
So, which number does 1111 1010represent? Since the first digit is a 1 we know it's a negative value. To find which value, do
那么，哪个数字1111 1010代表呢？由于第一个数字是 1，我们知道它是一个负值。要找到哪个值，请执行
-(flip(1111 1010) + 1) =
-(0000 0101 + 1)
-(0000 0110) =
-6
回答by Andreas Grapentin
~5 = -(5 + 1) = -6
~5 = -(5 + 1) = -6
so far so good. However, ~is not the two's complement, it's the binary inversion operator.
到目前为止，一切都很好。然而，~不是二进制的补码，而是二元求逆运算符。
5 = 0000 0101
flip : 1111 1010
which is -6
这是-6
does that make it clear?
这样说清楚了吗？
回答by xdazz
~is the Bitwise NOT operator (only inverts the bits of its operand).
~是按位非运算符（仅反转其操作数的位）。
For a positive number n,
对于正数n，
~n + 1 = -n
回答by Drazen Bjelovuk
Two's complement method- generates
-(x + 1).
二进制补码方法- 生成
-(x + 1).
Simply put, two's complement does not generate -(x + 1). One's complement does (i.e., ~ / bitwise NOT / flipping the bits).
简单地说，二进制补码不会生成-(x + 1)。一个的补码（即，〜/按位非/翻转位）。
Two's compliment (flip the bits, add 1) is the (-0averse) operation/encoding we use to express a negative number in pure bits (and derive it therefrom). Two's complement of xwill generate -x.
二进制补（翻转比特，添加1）是（-0厌恶）操作/编码，我们使用表达在纯位的负数（和导出它从其）。的补码x将生成-x。
~5is nothing more than flipping the bits 0000 0101to 1111 1010.
~5只不过是将位翻转0000 0101为1111 1010。
To determine the value of 1111 1010, we flip back to 0000 0101and add 1: 0000 0110 (-6).
为了确定 的值1111 1010，我们返回0000 0101并添加 1: 0000 0110 (-6)。
回答by Naveenk
Tild(~) -
波浪号(~) -
it is just flip(n). I.e. ~5 = flip(5). In java script numbers are always 64 bit signed. let us take Just 8 bit for reference,
它只是翻转（n）。即〜5 =翻转（5）。在 java 脚本中，数字总是 64 位有符号的。让我们只取 8 位作为参考，
5==> 0000 0101
~5 ==> filp(0000 0101)
~5 ==> 1111 1010 ==> -6
2' complement -
2' 补 -
It's filp(n) + 1.
它是 filp(n) + 1。
5 ==> 0000 0101
2's complement of 5 ==> flip(0000 0101) + 0000 0001
2's complement of 5 ==> 1111 1010 + 000 0001
2's complement of 5 ==> 1111 1011
