swap

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: how to provide a swap function for my class? There are some questions about this, but a lot of contradictions (person A giving solution A' with many upvotes with person B saying it's UB) or "only works if the compiler supports ADL" is answered. So, say I have the following template (container) class: template<typename T> class C { // ... void swap(C<T>& y) throw(); // C x; x.swap(y); } then what is the correct

问题 When I explicitly call rdd.cache, I can see from the spark console storage tab that only a fraction of the rdd is actually cached. My question is where are the remaining parts? How does Spark decide which part to leave in cache? The same question applies to the initial raw data read in by sc.textFile(). I understand these rdd's are automatically cached, even though the spark console storage table does not display any information on their cache status. Do we know how much of those are cached

问题 I'm having a hard time expressing this in Python. This is the description of what needs to be done. swap_cards: (list of int, int) -> NoneType swap_cards([3, 2, 1, 4, 5, 6, 0], 5) [3, 2, 1, 4, 5, 0, 6] swap_cards([3, 2, 1, 4, 5, 6, 0], 6) [0, 2, 1, 4, 5, 6, 3]` I've created 2 examples, but I don't know how to start the body of the function. 回答1: Sounds like some index notation is required here: >>> def swap_cards(L, n): ... if len(L) == n + 1: ... L[n], L[0] = L[0], L[n] ... return L ... L[n]

问题 A few lessons ago I learned about variables, and got a question in my homework about swapping two numbers - I used a third variable to solve this question. The solution looked somewhat like this: #include <stdio.h> int main(void) { int x, y; scanf("%d %d", &x, &y); // swappring the values int temp = x; x = y; y = temp; printf("X is now %d and Y is now %d", x, y); } Now I'm learning about functions, and I wanted to try and solve the previous question with a helper swap function. This is the

问题 I encountered this problem while solving a practice test Consider the following code written in a pass-by-reference language like FORTRAN and these statements about the code subroutine swap(ix,iy) it = ix ix = iy ! line L1 iy = it ! line L2 end program main ia = 3 ib = 8 call swap (ia, ib+5) print *, ia, ib end program Statements: The compiler will generate code to allocate a temporary nameless cell, initialize it to 13, and pass the address of the cell swap On execution the code will

问题 I want to swap two local variables using the xor algorithm, however it will not allow me to change the address of the variables. If I create pointers to the variables, it will allow it, but is it possible to do this without using pointers? I am trying to do this Point a = Point(); Point b = Point(1,1); &a ^= &b; &b ^= &a; &a ^= &b; This is the closest I have been able to get to what I want to do Point a = Point(); Point b = Point(1,1); Point *a_ptr = &a; Point *b_ptr = &b; a_ptr = (Point *)((

问题 I want to swap two local variables using the xor algorithm, however it will not allow me to change the address of the variables. If I create pointers to the variables, it will allow it, but is it possible to do this without using pointers? I am trying to do this Point a = Point(); Point b = Point(1,1); &a ^= &b; &b ^= &a; &a ^= &b; This is the closest I have been able to get to what I want to do Point a = Point(); Point b = Point(1,1); Point *a_ptr = &a; Point *b_ptr = &b; a_ptr = (Point *)((

问题 What is the proper way to enable my swap in STL algorithms? 1) Member swap . Does std::swap use SFINAE trick to use the member swap . 2) Free standing swap in the same namespace. 3) Partial specialization of std::swap . 4) All of the above. Thank you. EDIT: Looks like I didn't word my question clearly. Basically, I have a template class and I need STL algos to use the (efficient) swap method I wrote for that class. 回答1: 1) is the proper use of swap . Write it this way when you write "library"

问题 The problem is that this code won't interchange these 2 strings. I'm new to programming but I can tell that the problem is that swap function, but I do not know how to fix it. I tried to add strcpy instead of "=" in swap but that didn't worked. #include <stdio.h> #include <stdlib.h> void swap(char *t1, char *t2) { char *t; t=t1; t1=t2; t2=t; } int main() { char *s[2] = {"Hello", "World"}; swap(s[0], s[1]); printf("%s\n%s", s[0], s[1]); return 0; } 回答1: You want to use out parameters here, and

问题 How is it performing swapping? a=a+b b=a+b a=b+a I don't agree that it's swap to a book!!! The book options include "complements of values of a and b" ,"negate and b".Hope these options aren't satisfying it too??? 回答1: The swap is performed using XOR, which is typically written as a plus within a circle; for example: a := 5 b := 7 a := a xor b (2) b := a xor b (5) a := b xor a (7) 回答2: The correct algorithm should be: a = a + b b = a - b a = a - b 回答3: Actually, it can be done by two ways: