Write a program to swap two adjacent nodes by pointers c++

For an array, a swap method may be expected to change the value underneath references to a certain index of that array. When the function completes, a and b have been swapped. If you pass in node pointers to the respective nodes only, you would have to do another traversal to find the predecessors with this solution, which felt a bit awkward to me.

I do realize that this question has been asked almost two years ago and an answer long been accepted, but I have been a bit confused by the answers.

Of course, in the case of simple integers, as in the examples so far, that does apparently yield shorter, simpler code. The original values are not changed, because the function only swaps its own private copies. This causes a segmentation fault. Both C and Java use only parameters that pass by value, which means that the value of the actual parameter is used to initialize the formal parameter.

If the first node is at the head of the linked list, i. I found it more convenient to pass in the values of the nodes to swap, as opposed to node pointers. First, the definition of an auxiliary method: When swap is called, it is passed the addresses of a and b. This is why there is no semicolon at the end of swap int, a, bsince in the compiled code it would become a redundant semicolon at the end of a block although not an error.

C++ program to swap two numbers using pointers

The function needs a way to refer to the original variables, not copies of their values. Another way to say this is to say that the calling function is telling the called function where to find the variable.

Thus, i points to a draw an arrow from i to a and j points to b draw another arrow from b to j. Notice that the code for the actual swap is simple: We gave it a way to refer to our pointer variables, so it can change them!

The method sets n to point to the node containing the passed value. Now, we are left with just two more conditionals, neither of which seemed trivial to avoid. How do we do that? However, when we discuss linked lists with nodes containing integers it is usually as a stand-in for the backing data structure of a more complex and generic container.

If we pass pointers, the pointers will simply be copied not the values they point to to the arguments. And swap4 is changing the values our variables point to, not the pointers! If the linked list was, as in the example of the array, based on indexing semantics then the position in the node might simply represent the order in which the cars are loaded onto a ship for transport.

I am not quite sure, but it sounded like Smashery purposefully left those repeated assignments out of logical rigor and to better illustrate the procedure - I may have misunderstood, though. Another very good way to swap in C perhaps the best way uses the C preprocessor, which we will study later.

If we cannot distinguish nodes by these values, e. Now what happens if we have two pointer variables and want to swap the pointers themselves as opposed to the values they point to? For simple variables C allows one to pass the address of the variable explicitly.

I found detecting adjacency through position, rather than pointer comparisons, more readable. For now, a preprocessor function like swap below does a textual substitution, before the actual compiler is invoked.

If we pass pointers to our variables into the function, the function can swap the values in our variables, instead of its own argument copies. The "bubble sort" program below illustrates this. I do admit, though, that this might depend on the semantics of the container.

The scanf function is using pointers to put the value it reads back into the variable you have passed. The program here is only presented as what could be done, not as an example of how to do swaps. Now draw the two pointers i and j, along with the integer t. If they are adjacent, there are no nodes between the nodes to swap that need updating, so simply linking the second node to the first is all that is left to do.

Thus we need our own wrapper class, which I have called MyInteger below. If I am wrong about that and that approach would in fact solve this problem then I would have been able to eliminate the last conditional in the code below, which I was trying to get rid off when I first looked on the Internet for a solution to swapping nodes without special-casing adjacent nodes.

That would mean that the references are not meant to refer to a specific object, but to a position in a container that one can index.

Some of this may have been more fitting as comments, but I do not have the reputation to comment, yet. We pass it their addresses!I am trying to make a swapNode function that can take any two nodes and swap them. I've made an algorithm that works if they're at least 2 nodes away, but I can't seem to come up with an algorithm.

Pairwise swap elements of a given linked list. Given a singly linked list, write a function to swap elements pairwise. // Java program to pairwise swap elements of a linked list. class LinkedList { Node head; If there are 2 or more than 2 nodes in Linked List then swap the first two nodes and recursively call for rest of.

Swapping two pointers [duplicate] Ask Question. You can of course write swap(int*& x, int*& y), but that would still not allow you to swap the pointers to x and y in main because those are immutable (in C++ parlance, "rvalues").

It would allow you to successfully swap two mutable pointers though. One thought on “ C++ program to swap two numbers using pointers ” David Thiessen February 22, Here is how I rewrote: //this program will swap two ints using ptrs.

#include. using namespace std; int main() {int* a = new int. I have been struggling to understand the different behaviour when swapping pointers in C. If I want to swap two int pointers, then I can do void intSwap (int *pa, int *pb){ int temp = *pa. Now draw the two pointers i and j, along with the integer t.

When swap is called, it is passed the addresses of a and b. Swapping in Java: which we probably won't study in this course. However, below is a C++ swap program using this feature.

C Program to Accept an Array & Swap Elements using Pointers Download
Write a program to swap two adjacent nodes by pointers c++
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