operator-keyword

问题 I have a class named ThreeDigits on c++ code. I overloaded the + operand, this way: ThreeDigits* ThreeDigits::operator+(const ThreeDigits &number) const { double result= getNumber()+number.getNumber(); ThreeDigits* new_result=new ThreeDigits(result); return new_result; } but when I write on the main function: ThreeDigits* first=new ThreeDigits(2.55998); ThreeDigits* second=new ThreeDigits(5.666542); ThreeDigits* result=first+second; I get the following compilation error: invalid operands of

问题 When someone is calling a function by "SOME" or "ANY" makes me unsure about this. Can I think about "SOME" as "OneOf" or "OneFrom"? Like an array (table) searching function? If yes, then what's the difference between SOME and IN? I am total newbie with SQL Sorry for my bad english, for some reason I think I am little overtired to use it correctly now 回答1: Check the following link for some examples that should clarify the difference between them: http://technet.microsoft.com/en-us/library

问题 this code doesn't work int main(){ cout << 5 ? (5 ? 0 : 2) : 5; system("pause"); return 0; } this code works int main(){ cout << (5 ? (5 ? 0 : 2) : 5); system("pause"); return 0; } can't understand why? 回答1: cout << 5 ? (5 ? 0 : 2) : 5; is parsed as (cout << 5) ? (5 ? 0 : 2) : 5; 回答2: This is due to operator precedence rules. << has higher precedence than ? , so your first expression is parsed as: (cout << 5) ? (5 ? 0 : 2) : 5; Brackets are necessary in this case to get the parse you want. 来源

问题 So I want to overload operator+ . Here is what I have so far, but it's still not working. How would I go in writing the syntax? Header file: private: int month; int year; int day; public: upDate(); upDate(int M, int D, int Y); void setDate(int M, int D, int Y); int getMonth(); int getDay(); int getYear(); int getDateCount(); string getMonthName(); friend upDate operator+(const upDate &lhs, const upDate &rhs); My .cpp file upDate::upDate() { month = 12; day = 12; year = 1999; } upDate::upDate

问题 So I want to overload operator+ . Here is what I have so far, but it's still not working. How would I go in writing the syntax? Header file: private: int month; int year; int day; public: upDate(); upDate(int M, int D, int Y); void setDate(int M, int D, int Y); int getMonth(); int getDay(); int getYear(); int getDateCount(); string getMonthName(); friend upDate operator+(const upDate &lhs, const upDate &rhs); My .cpp file upDate::upDate() { month = 12; day = 12; year = 1999; } upDate::upDate

问题 So I want to overload operator+ . Here is what I have so far, but it's still not working. How would I go in writing the syntax? Header file: private: int month; int year; int day; public: upDate(); upDate(int M, int D, int Y); void setDate(int M, int D, int Y); int getMonth(); int getDay(); int getYear(); int getDateCount(); string getMonthName(); friend upDate operator+(const upDate &lhs, const upDate &rhs); My .cpp file upDate::upDate() { month = 12; day = 12; year = 1999; } upDate::upDate

问题 I would like to know if anybody knew what a . after an integer in C means. i have this piece of code i want to convert and that is the only thing i am not sure of what it does. if (y>=0.) what does the . here do? full code: double angleOf(double x, double y) { double dist=sqrt(x*x+y*y) ; if (y>=0.) return acos( x/dist); else return acos(-x/dist)+.5*CIRCLE_RADIANS; } 回答1: It's same as 0.0 , it will treat it as double instead of an integer, so you don't need to cast it. 回答2: The trailing dot

问题 I'm getting to know hyperledger composer angular apps. This piece of code that yeoman generator produces puzzle me. The add method executes return this.http.post and it returns a response object, that is chained to a map operator to convert to json output. But all references I could find to map operator show that its argument must be specified, like an arrow function (v)=> {some instructions to perform on v here}); , or as an anonymous function (f(v){some instructions here}) ; I've seem the

问题 my aim is to write a little prove assistant in prolog. My first step is to define the logical connectives as follows: :-op(800, fx, -). :-op(801, xfy, &). :-op(802, xfy, v). :-op(803, xfy, ->). :-op(804, xfy, <->). :-op(800, xfy, #). The last operator # just has the meaning to be the placeholder for & , v , -> or <-> . My problem is, I don't know how I it is possible to define this in prolog. I tried to solve my problem in the following way: X # Y :- X v Y; X & Y; X -> Y; X <-> Y. but the

问题 Visual Studio 2019's code analysis and code suggestions started to highlight every line of code where I call a method that returns a value but don't use that value at all and tells me to use the discard operator _ . I don't fully understand why that matters and it even seems wrong for Fluent API style code. Is there a functional difference between the two following lines? private int SomeMethod() => 0; ... SomeMethod(); _ = SomeMethod(); ... Would it matter more if the return value is a