variable-assignment

问题 While looking at an answer posted recently on SO, I noticed an unfamiliar assignment statement. Instead of the usual form of myVar<- myValue , it used the for myVar[]<- myValue . Personally, I had never seen such an assignment, but it had a highly useful effect-- it reshaped the assigned data myValue to the shape of myVar. I would like to use this in my code. However the documentation for "<-" seems to be silent on it. Is this a well established feature and one can rely on it to work in all

问题 I'm trying to create a function servo_to_quadrant that returns the value servo_quadrant . Questions similar to this one have involved there being an issue with a global variable outside of the function. I don't think that's the issue in this case, as the variable is only needed from within the function (although I could be wrong). Code: def servo_to_quadrant(servo_val): if servo_val < 0: 360 + servo_val if servo_val >= 360: servo_val = servo_val - 360 if servo_val >= 0 and servo_val < 90:

问题 I'm trying to create a function servo_to_quadrant that returns the value servo_quadrant . Questions similar to this one have involved there being an issue with a global variable outside of the function. I don't think that's the issue in this case, as the variable is only needed from within the function (although I could be wrong). Code: def servo_to_quadrant(servo_val): if servo_val < 0: 360 + servo_val if servo_val >= 360: servo_val = servo_val - 360 if servo_val >= 0 and servo_val < 90:

问题 I have an example of a program that creates an array, and then attempts to assign the value of that array multiple times into another array as a multidimensional array. $a =@(0,0,0) $b = @($a,$a,$a) $b[1][2]=2 $b 'And $a is changed too:' $a The output is: PS E:\Workarea> .\what.ps1 0 0 2 0 0 2 0 0 2 And $a is changed too: 0 0 2 So in this instance, the variable is actually pointing to the original variable. This is very unexpected behavior. It's rather neat that one can do this, although I

问题 In Swift, why does var x: Int? = nil if let y: Int? = x { ... } behave differently from if let y: Int? = nil { ... } My understanding of why the first case succeeds suggests that the second should as well, so I must not really be understanding. The latter is not failing because of an invalid assignment, nor because of optional chaining; and otherwise it seems the same as the former. Why does the latter fail, and how is it different from the former. Exactly at what point, and for what reason,

问题 I know I can use the comma operator like this for (int i = 1, j = 15; j>10; i++, j--) { // do something neat } but some articles seem to suggest that the comma operator can be used outside of the for loop declaration, for example int j = 2, k = 4 ; int x ; // Assignment statement with comma operator x = j + 1, k ; source: http://www.cs.umd.edu/~clin/MoreJava/ControlFlow/comma.html or int x = (expression) ? (i++,2) : 3; source: https://stackoverflow.com/a/12047433/1084813 This would be a neat

问题 How would I express the following java code in scala? a = b = c; By the way, I'm re-assigning variables (not declaring). 回答1: The closest shortcut syntax in Scala can only be used when you declare a var or val . scala> val c = 1 c: Int = 1 scala> val a, b = c a: Int = 1 b: Int = 1 From the Scala Reference, Section 4.1 A value declaration val x 1 , ... , x n : T is a shorthand for the sequence of value declarations val x 1 : T ; ...; val x n : T. A value definition val p 1 , ..., p n = e is a

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: How can I change the values of multiple points in a matrix? I have a matrix A and three vectors of the same length, r , holding the indexes of the rows to assign to, c , holding the indexes of the columns to assign to, and v containing the actual values to assign. What I want to get is A(r(i),c(i))==v(i) for all i . But doing A(r,c)=v; Doesn't yield the correct result as matlab interprets it as choosing every

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: How can I change the values of multiple points in a matrix? I have a matrix A and three vectors of the same length, r , holding the indexes of the rows to assign to, c , holding the indexes of the columns to assign to, and v containing the actual values to assign. What I want to get is A(r(i),c(i))==v(i) for all i . But doing A(r,c)=v; Doesn't yield the correct result as matlab interprets it as choosing every

问题 When I try to do this... Item[,] array = new Item[w, h]; // Two dimensional array of class Item, // w, h are unknown at compile time. foreach(var item in array) { item = new Item(); } ...I get Cannot assign to 'item' because it is a 'foreach iteration variable' . Still, I'd like to do that. The idea is to assign default Item class values to existing item. 回答1: Okay, now that we know your aim instead of how you were trying to achieve it, it's much easier to answer your question: you shouldn't