bitwise-operators

问题 I've come up with several manual ways of doing this, but i keep wondering if there is something built-in .NET that does this. Basically, i want to reverse the bit order in a byte, so that the least significant bit becomes the most significant bit. For example: 1001 1101 = 9D would become 1011 1001 = B9 On of the ways to do this is to use bitwise operations if following this pseudo code: for (i = 0; i<8; i++) { Y>>1 x= byte & 1 byte >>1 y = x|y; } I wonder if there is a function somewhere that

问题 Say I was to write this: a=01100001 b=01100010 c=01100011 d=01100100 e=01100101 each letter resembles the given numbers now how would I deal with the resembling values: Python would want to do this: a + b = 2200011 but what I want it to do is this if 0 and 0 are attempted to be added together show 1 if 1 and 0 are attempted to be added together show 0 if 0 and 1 are attempted to be added together show 0 if 1 and 1 are attempted to be added together show 0 What I wish to do is a + b = 10011100

问题 Why is it that the bitwise NOT operator ( ~ in most languages) converts the following values like so: -2 -> 1 -1 -> 0 0 -> -1 1 -> -2 Shouldn't -2 convert to 2 , 1 convert to -1 , etc.? 回答1: See two's complement for the representation of negative integers in many languages. As you can see, -2 is represented by 1111110 ; if you invert all those bits you get 0000001 , i.e. a value of 1. 回答2: It helps if you look at it in binary. First of all, as you know, negative numbers are expressed as

问题 Sorry for the very basic question. What does the & operator do in this SQL WHERE (sc.Attributes & 1) = 0 sc is an alias for a table which contains a column attributes . I'm trying to understand some SQL in a report and that line is making it return 0 entries. If I comment it out it works. I have limited SQL knowledge and I'm not sure what the & 1 is doing. 回答1: & is the bitwise logical and operator - It performs the operation on 2 integer values. WHERE (sc.Attributes & 1) = 0 The above code

问题 I'm trying to do some bitwise operations in Javascript, 0xff000000 | 0x00aabbcc Which I expect to give me 0xffaabbcc // == 4289379276; However when running this, I get the result -5588020. I expect this has something to do with the fact that bitwise operations in javascript only operate on 32 bit numbers, but aren't the two numbers in question <= 32bit anyway? Can someone point out where I'm going wrong and how I can get the desired result? I've tried the technique outlined at How to do

问题 In c ~ is 1's complement operator. This is equivalent to: ~a = -b + 1 So, a - ~b -1 = a-(-b + 1) + 1 = a + b – 1 + 1 = a + b Can anyone explains this to me? 回答1: From elementary school math we know a = -(-a); From twos complement we know that -a = (~a) + 1 (invert and add one) so we know that a + b = a - (-b) elementary math = a - (~b + 1) twos complement = a - (~b) - 1 distribute the negative (elementary math) 回答2: You are right that ~ is always 1's complement (aka bitwise not) in c. Where

问题 Considering I have this fields in a Base object: //these fields have their bits constantly permuted //and have their values defined to "011233455677..." //to integers acts like Strings var ul = 0x011233 var ur = 0x455677 var dl = 0x998bba var dr = 0xddcffe And considering I have this method which operates those fields as String values: private fun Cubo.isSolved(): Boolean { val solved = Base() //function to append "leading zero" to the hex integer fun fill(s: String) = if (s.length == 5) "0$s

问题 How do you get number like -10 from these bit shifting practice problems? From what I understand X*32 can be written as x<<5 . But how are you to get numbers like x*66 , or X*(-10) ? 回答1: General Explanation Bit shifting is primarily aimed to shift the binary representation of a number. It is not for multiplication. 23 = 0001 0111 23 << 1 = 0001 0111 << 1 = 0010 1110 = 46 However, as the binary representation of a number is changed, the number it represents is also changed. This is just how

问题 I want to implement void bitwise_and( char* __restrict__ result, const char* __restrict__ lhs, const char* __restrict__ rhs, size_t length); or maybe a bitwise_or() , bitwise_xor() or any other bitwise operation. Obviously it's not about the algorithm, just the implementation details - alignment, loading the largest possible element from memory, cache-awareness, using SIMD instructions etc. I'm sure this has (more than one) fast existing implementations, but I would guess most library

问题 This W3Schools page describes bitwise AND as: Sets each bit to 1 if both bits are 1. And an example is given: 5 & 1 returns 1, same as 0101 & 0001 returns 1. As far as I know, 0101 are 4 bits and 0001 are another 4 bits. So, what is meant by "if both bits are 1"? What are these bits they are talking about? 回答1: A bitwise operation is exactly bitwise, each bit goes into the CPU and gets combined with another bit. So 0001 AND 0101, each of the four output bits are calculated according to that