swap

问题 #include <iostream> struct H { void swap(H &rhs); }; void swap(H &, H &) { std::cout << "swap(H &t1, H &t2)" << std::endl; } void H::swap(H &rhs) { using std::swap; swap(*this, rhs); } int main(void) { H a; H b; a.swap(b); } And this is the result: swap(H &t1, H &t2) In the code above, I try to define a swap function of H . In the function void H::swap(H &rhs) , I use an using declaration to make the name std::swap visible. If there isn't an using declaration, the code cannot be compiled

问题 I've been trying to learn sed and the examples I've found here are for swapping dates from 05082012 to 20120805 and I'm having trouble adapting them to my current need. I need to convert an IP address 10.4.13.22 to a reverse lookup of 22.13.4.10 for a nsupdate script. My biggest problem is the fact that sometimes each octet can change lengths e.g. 10.4.13.2 and 10.19.8.126 Thanks for any help! echo 10.0.2.99 | sed 's/\(....\)\(....\)/\2\1/' this is currently what I've tried, just based off

问题 I have a class with a vector of strings and a function that assigns to that vector. I am changing my function to only assign to the vector if it's successful. To do that I use a temporary vector of strings in the function and then if the function is successful I assign to the vector of strings in the class. For example: class test { vector<string> v; void Function() { vector<string> temp; v = temp; // Is this better? v.swap( temp ); // Or instead is this better? } }; Thanks 回答1: In C++11,

问题 About swap , in C++, we can swap two by std::swap(x, y); . x and y are passed into swap as reference . But in Python, can we also write a swap function which can do the swap the same way as in C++? The Python version of swap I implemented is kinda stupid: def swap_in_python(x, y): return y, x #so when swapping a and b, I usually do it like this a, b = swap_in_python(a, b) This is really cumbersome, but we can't pass reference or pointer as what we can do in C++, right? EDIT: Is there any

问题 I am trying to swap two nodes in a doubly linked list. Below is the part of program having swap function. int swap (int x, int y) { struct node *temp = NULL ; struct node *ptr1, *ptr2; temp = (struct node *)malloc(sizeof(struct node)); if (head == NULL ) { printf("Null Nodes"); } else { ptr1 = ptr2 = head; int count = 1; while (count != x) { ptr1 = ptr1->next; count++; } int count2 = 1; while (count2 != y) { ptr2 = ptr2->next; count2++; } ptr1->next->prev = ptr2; ptr1->prev->next = ptr2; ptr2

问题 This question already has answers here : Is JavaScript a pass-by-reference or pass-by-value language? (30 answers) Closed 3 years ago . I am not able to achieve the desired result for this swap function below, where I want the values printed as 3,2 function swap(x,y){ var t = x; x = y; y = t; } console.log(swap(2,3)); Any clue will be appreciated ! 回答1: Your function is swapping the values internally, but the function does not return a value. The following method returns an array of values in

问题 I have a list of 6 items that are in a global div (navigationagence) Right now I am able to add a class on click but right now they adds up which means that once my six items are clicked they all end up with the currentagence class. I want to be able to remove the add a class to the clicked item but remove it to the other, How can I achieve that? Here is the jquery code I am using right now. $("#navigationagence ul li").click(function () { $(this).toggleClass("currentagence"); }); 回答1: You

问题 I know that it is possible to swap the value of two variables like so #include <stdio.h> void swap(int *x, int *y); int main(){ int x=5,y=10; swap(&x, &y); printf("x: %d, y: %d\n", x, y); return 0; } void swap(int *x, int *y){ int temp; temp=*x; *x=*y; *y=temp; } But is it possible to swap the addresses of those two variables? And I don't mean just making a pointer to them and then swapping the values held by the pointers, I mean actually swapping the two, so that after the swap function the

问题 I have a list and I need to swap the 1st element in the list with the maximum element in the list. But why does code 1 work while code 2 doesn't: code 1: a = list.index(max(list)) list[0], list[a] = list[a], list[0] code 2: list[0], list[list.index(max(list))] = list[list.index(max(list))], list[0] I thought Python would first evaluate the right-hand side before assigning it to the names on the left? 回答1: Python stores results in multiple targets from left to right , executing the assignment

问题 STL implements a generic std::swap function to swap 2 values. It can be presented in the following way: template <class T> void swap (T& a, T& b) { T c(std::move(a)); a=std::move(b); b=std::move(c); } However, there is a XOR swap algorithm to swap 2 integers (http://en.wikipedia.org/wiki/XOR_swap_algorithm): void swap_u( size_t& x, size_t& y ) { x = x^y; y = x^y; x = x^y; } My questions: Is it an optimization nowadays (on x86 or arm )? Does C++ standard favor this kind of optimization? Are