operator-keyword

问题 If I have two structs: struct A { float x, y; inline A operator*(A b) { A out; out.x = x * b.x; out.y = y * b.y; return out; } } And an equivalent struct struct B { float x, y; } inline B operator*(B a, B b) { B out; out.x = a.x * b.x; out.y = a.y * b.y; return out; } Would you know of any reason for B's operator* to compile any differently, or run any slower or faster than A's operator* (the actual actions that go on inside the functions should be irrelevant)? What I mean is... would

问题 was it possible to add operator func to Swift class subscript method var x = ["dkfkd", "dkff"] x[2] ??= "mmmm" // equal to x[2] = x[2] ?? "mmmm" 回答1: This isn’t related to the subscript operator, but more a question of how to define a ??= operator. Which you can do, but it might not work quite the way you expect. Here’s a possible implementation: // first define the ??= operator infix operator ??= { } // then some pretty standard logic for an assignment // version of ?? func ??=<T>(inout lhs:

问题 int m = 5, d = 12, y = 1975, val; // May 12, 1975 Can someone please explain the function/purpose of the comma operator in the line of code below: val = (d+=m<3?y--:y-2,23*m/9+d+4+y/4-y/100+y/400)%7; The above line was written by Mike Keith to calculate the day of the week given the date (d = day, m = month, y = year). Where Sunday = 0, Monday = 1, Tuesday = 2, Wednesday = 3, Thursday = 4, Friday = 5, Saturday = 6. I understand that the y-- gets executed if d+=m<3 is true, else the y-2 is

问题 trying to get the operator to work, but throwing me bunch of errors: my header file template <unsigned short n> class Vector { public: std::vector<float> coords; Vector(); Vector(std::vector<float> crds); friend std::ostream& operator <<(std::ostream& out, const Vector& v); }; template <unsigned short n> Vector<n>::Vector() { coords.assign(n, 0.0); } template <unsigned short n> std::ostream& operator<<(std::ostream& out, const Vector<n>& v) { out << "(" << v.coords[1] << " - " << v.coords[2]

问题 i have a verilog code in which there is a line as follows: parameter ADDR_WIDTH = 8 ; parameter RAM_DEPTH = 1 << ADDR_WIDTH; here what will be stored in RAM_DEPTH and what does the << operator do here. 回答1: << is a binary shift, shifting 1 to the left 8 places. 4'b0001 << 1 => 4'b0010 >> is a binary right shift adding 0's to the MSB. >>> is a signed shift which maintains the value of the MSB if the left input is signed. 4'sb1011 >> 1 => 0101 4'sb1011 >>> 1 => 1101 Three ways to indicate left

问题 I just tried to make a simple class that lets me figure out the length of a file: public class Size { long s = 0; int a; public static void main(String[]args){ new Size(); } Size(){ try{ FileInputStream str = new FileInputStream("E:/Eclipse/Resources/smile.jpg"); while(a != null){ s++; } }catch (IOException e){ e.printStackTrace(); } } } I run into a problem with while(a != null) I get the Error: The operator != is undefined for the argument type(s) int, null Any ideas why it's blocking the

问题 What do I need to change to make this work? class A: @staticmethod def __getitem__(val): return "It works" print A[0] Note that I am calling the __getitem__ method on the type A . 回答1: When an object is indexed, the special method __getitem__ is looked for first in the object's class. A class itself is an object, and the class of a class is usually type . So to override __getitem__ for a class, you can redefine its metaclass (to make it a subclass of type ): class MetaA(type): def __getitem__

问题 My Question: I'm trying to overload the assignment operator for pointers to two different classes. Here is an example: dc.h: #ifndef DC_H_ #define DC_H_ #include "ic.h" class dc { double d; char c; public: dc(): d(0), c(0) { } dc(double d_, char c_): d(d_), c(c_) { } dc* operator=(const ic* rhs); ~dc() { } }; #endif /* DC_H_ */ class ic.h: #ifndef IC_H_ #define IC_H_ class ic { int i; char c; public: ic(): i(0), c(0) { } ic(int i_, char c_): i(i_), c(c_) { } ~ic() { } }; #endif /* IC_H_ */ dc

问题 I am a groovy newbie. Maybe this is a piece of cake, but I want to overload the + operator for arrays/lists to code like this def a= [1,1,1] def b= [2,2,2] assert [3,3,3] == a + b 回答1: I wouldn't recommend globally overriding well-established behaviors. But, if you insist, this will do as you ask: ArrayList.metaClass.plus << {Collection b -> [delegate, b].transpose().collect{x, y -> x+y} } A more localized alternative would be to use a category: class PlusCategory{ public static Collection

问题 I am trying to add a class object with a number, but I'm confused on how to go about adding a class object with two numbers. For example, this is my hypothetical add class method: class A: def __add__(self, b): return something I know how to add this so far: object = A() print(object + 1) But, what if I want to add it like this? object = A() print(object + 1 + 2) Should I use *args for the add class method? 回答1: No, you can't use multiple arguments. Python executes each + operator separately,