binary-operators

c++ multiple enums in one function argument using bitwise or “|”

由 a 夏天 提交于 2019-12-12 07:48:55
问题 I recently came across some functions where you can pass multiple enums like this: myFunction(One | Two); Since I think this is a really elegant way I tried to implement something like that myself: void myFunction(int _a){ switch(_a){ case One: cout<<"!!!!"<<endl; break; case Two: cout<<"?????"<<endl; break; } } now if I try to call the function with One | Two, I want that both switch cases get called. I am not really good with binary operators so I dont really know what to do. Any ideas

Bitmasking conversion of CPU ids with Go

由 对着背影说爱祢 提交于 2019-12-11 00:34:28
问题 I have a mask that contains a binary counting of cpu_ids ( 0xA00000800000 for 3 CPUs) which I want to convert into a string of comma separated cpu_ids: "0,2,24" . I did the following Go implementation (I am a Go starter). Is it the best way to do it? Especially the handling of byte buffers seems to be inefficient! package main import ( "fmt" "os" "os/exec" ) func main(){ cpuMap := "0xA00000800000" cpuIds = getCpuIds(cpuMap) fmt.Println(cpuIds) } func getCpuIds(cpuMap string) string { //

Unary Operations fused with assignment

由 余生长醉 提交于 2019-12-10 20:46:43
问题 Doubtful result in the following code: public static void main (String[] args) { int i = 2; i = i+=2 + i++; System.out.println(i); } Was expecting 8 as output, as 'i+=2' should update i, but its not behaving so. Output: 6 I infer that the short-hand assignment operator is returning 4 as expected but not updating the same in variable i. Any explanation will be appreciated. 回答1: i++ is a postfix increment - it increments i, then essentially returns the old value of i. The equivalent prefix

Define assigment operator that change the value of some “this” in C# [duplicate]

由 霸气de小男生 提交于 2019-12-08 15:22:19
问题 This question already has answers here : Overloading assignment operator in C# (3 answers) Closed 2 months ago . I want to define an operator= that try to change the inner value of the class I'm implementing a variatic type in c# that may contain an int , bool or double and I want to overrload the = operator so I can do something like: Variable bar = new Variable(1.2); bar = 2.3; I internaly keep the initialized type, so you can't change type over execution, so if I do: Variable foo = new

C++ Binary operators order of precedence

由 感情迁移 提交于 2019-12-04 12:19:52
In what order are the following parameters tested (in C++)? if (a || b && c) { } I've just seen this code in our application and I hate it, I want to add some brackets to just clarify the ordering. But I don't want to add the brackets until I know I'm adding them in the right place. Edit: Accepted Answer & Follow Up This link has more information, but it's not totally clear what it means. It seems || and && are the same precedence, and in that case, they are evaluated left-to-right. http://msdn.microsoft.com/en-us/library/126fe14k.aspx tzot From here : a || (b && c) This is the default

C reverse binary [duplicate]

由 有些话、适合烂在心里 提交于 2019-12-03 15:03:29
问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: C reverse bits in unsigned integer How can I reverse a binary number only using binary operators? E.g: 11100000 -> 00000111 00110100 -> 00101100 00111111 -> 11111100 回答1: For this sort of thing I recommend that you take a look at the awesome page Bit Twiddling Hacks. Here is just one example solution taken from that page: Reverse the bits in a byte with 3 operations (64-bit multiply and modulus division)

Weird behaviour of bit-shifting with byte in Java

由 和自甴很熟 提交于 2019-12-01 22:14:16
问题 As I was using bit-shifting on byte , I notice I was getting weird results when using unsigned right shift ( >>> ). With int , both right shift (signed: >> and unsigned: >>> ) behave as expected: int min1 = Integer.MIN_VALUE>>31; //min1 = -1 int min2 = Integer.MIN_VALUE>>>31; //min2 = 1 But when I do the same with byte , strange things happen with unsigned right shift: byte b1 = Byte.MIN_VALUE; //b1 = -128 b1 >>= 7; //b1 = -1 byte b2 = Byte.MIN_VALUE; //b2 = -128 b2 >>>= 7; //b2 = -1; NOT 1!

Weird behaviour of bit-shifting with byte in Java

由 ぃ、小莉子 提交于 2019-12-01 18:55:24
As I was using bit-shifting on byte , I notice I was getting weird results when using unsigned right shift ( >>> ). With int , both right shift (signed: >> and unsigned: >>> ) behave as expected: int min1 = Integer.MIN_VALUE>>31; //min1 = -1 int min2 = Integer.MIN_VALUE>>>31; //min2 = 1 But when I do the same with byte , strange things happen with unsigned right shift: byte b1 = Byte.MIN_VALUE; //b1 = -128 b1 >>= 7; //b1 = -1 byte b2 = Byte.MIN_VALUE; //b2 = -128 b2 >>>= 7; //b2 = -1; NOT 1! b2 >>>= 8; //b2 = -1; NOT 0! I figured that it could be that the compiler is converting the byte to int

No binary operators for structured arrays in Numpy?

由 耗尽温柔 提交于 2019-11-30 19:21:40
Okay, so after going through the tutorials on numpy's structured arrays I am able to create some simple examples: from numpy import array, ones names=['scalar', '1d-array', '2d-array'] formats=['float64', '(3,)float64', '(2,2)float64'] my_dtype = dict(names=names, formats=formats) struct_array1 = ones(1, dtype=my_dtype) struct_array2 = array([(42., [0., 1., 2.], [[5., 6.],[4., 3.]])], dtype=my_dtype) (My intended use case would have more than three entries and would use very long 1d-arrays.) So, all goes well until we try to perform some basic math. I get errors for all of the following:

Compiler error when comparing values of enum type with associated values?

由 [亡魂溺海] 提交于 2019-11-27 16:20:37
class MyClass { enum MyEnum { case FirstCase case SecondCase(Int) case ThirdCase } var state:MyEnum! func myMethod () { if state! == MyEnum.FirstCase { // Do something } } } I get the compiler error pointing at the if statement:: Binary operator '==' cannot be applied to two 'MyClass.MyEnum' operands If instead, I use a switch statement, there is no problem: switch state! { // Also, why do I need `!` if state is already an // implicitly unwrapped optional? Is it because optionals also // are internally enums, and the compiler gets confused? case .FirstCase: // do something... default: // (do
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