function

问题 I'm trying to understand this code istream &read(istream &is, Sales_data &item) { double price = 0; is >> item.bookNo >> item.units_sold >> price; item.revenue = price * item.units_sold; return is; } ostream &print(ostream &os, const Sales_data &item) { os << item.isbn() << " " << item.units_sold << " " << item.revenue << " " << item.avg_price(); return os; } I don't understand what are these function , also I can't understand why we use istream for reading and ostream for printing instead of

问题 I'm not sure if this is possible but i'm open to ideas. I have a c++ function. It does some calculation to arrays that are being defined by users as inputs and will generate two output values. Let's call it "myfunction" and it looks something like this: void myfunction(double array1[18],double array[9],double array [2],double *output1, double *output2) I want to make this function more generic so that it is able to take in arrays of different size. Meaning, I want users of this function to be

问题 I have a VB.NET function as below, the parameter 'x' that is passed to the function is of Type 'Single'. However, I want to write the function so that it can accept any numeric type such as 'Single', 'Double' and 'Integer'. I know one way of doing that is to write 3 functions with the same names, but it would be so tedious. Can anyone suggest any idea? Thank you. Public Function Square(x As Single) As Single Return x * x End Function 回答1: try following method Public Function Square(Of T)

问题 Approach 1 f1 <- function(x) { # Do calculation xyz .... f2 <- function(y) { # Do stuff... return(some_object) } return(f2(x)) } Approach 2 f2 <- function(y) { # Do stuff... return(some_object) } f3 <- function(x) { # Do calculation xyz .... return(f2(x)) } Assume f1 and f3 both do the same calculations and give the same result. Are there any significant advantages in using approach 1, calling f1() , vs approach 2, calling f3() ? Is a certain approach more favourable when: large data is being

问题 Approach 1 f1 <- function(x) { # Do calculation xyz .... f2 <- function(y) { # Do stuff... return(some_object) } return(f2(x)) } Approach 2 f2 <- function(y) { # Do stuff... return(some_object) } f3 <- function(x) { # Do calculation xyz .... return(f2(x)) } Assume f1 and f3 both do the same calculations and give the same result. Are there any significant advantages in using approach 1, calling f1() , vs approach 2, calling f3() ? Is a certain approach more favourable when: large data is being

问题 Approach 1 f1 <- function(x) { # Do calculation xyz .... f2 <- function(y) { # Do stuff... return(some_object) } return(f2(x)) } Approach 2 f2 <- function(y) { # Do stuff... return(some_object) } f3 <- function(x) { # Do calculation xyz .... return(f2(x)) } Assume f1 and f3 both do the same calculations and give the same result. Are there any significant advantages in using approach 1, calling f1() , vs approach 2, calling f3() ? Is a certain approach more favourable when: large data is being

问题 This question already has answers here : Destructuring to get the last element of an array in es6 (12 answers) Closed 3 years ago . let array = [1,2,3,4,5,6,7,8,9,0] Documentation is something like this [first, ...rest] = array will output 1 and the rest of array Now is there a way to take only the first and the last element 1 & 0 with Destructuring ex: [first, ...middle, last] = array I know how to take the first and last elements the other way but I was wondering if it is possible with es6

问题 I have 2 functions fun1 and fun2 which take as inputs a string and a number respectively. The also both get as input the same variable a . This is the code: a = ['A','X','R','N','L'] def fun1(string,vect): out = [] for letter in vect: out. append(string+letter) return out def fun2(number,vect): out = [] for letter in vect: out.append(str(number)+letter) return out x = fun1('Hello ',a) y = fun2(2,a) The functions perform some nonsense operations. My goal would be to rewrite the code in such a

问题 I'm using Python and OpenCV for some vision application. I need to save mouse position in variables and I don't know how. I can get the current mouse position to print in window, but can't save it to variable. My problem is similar to this one only I work in python: OpenCV Return value from mouse callback function I define my function like this (for printing mouse position): def mousePosition(event,x,y,flags,param): if event == cv2.EVENT_MOUSEMOVE: print x,y I use it in my program like this:

问题 I'm using Python and OpenCV for some vision application. I need to save mouse position in variables and I don't know how. I can get the current mouse position to print in window, but can't save it to variable. My problem is similar to this one only I work in python: OpenCV Return value from mouse callback function I define my function like this (for printing mouse position): def mousePosition(event,x,y,flags,param): if event == cv2.EVENT_MOUSEMOVE: print x,y I use it in my program like this: