how to swap arrays without copying elements-CodePudding

I'd like to swap two integer arrays without copying their elements :

int  Z1[10],Z2[10];
std::swap(Z1,Z2);  // works
//int *tmp;*tmp=*Z1;*Z1=*Z2;*Z2=*tmp; // doesn't work
[ expressions involving Z1,Z2 ]

In the third line I commented out what I tried and didn't work Is there a way to do this by swapping pointers instead...

CodePudding user response：

how to swap arrays without copying elements

By virtue of what swapping is, and what arrays are, it isn't possible to swap arrays without copying elements (to be precise, std::swap swaps each element and a swap is conceptually a shallow copy).

What you can do is introduce a layer of indirection. Point to the arrays with pointers. Then, swapping the pointers will swap what arrays are being pointed without copying elements:

int* ptr1 = Z1;
int* ptr2 = Z2;
std::swap(ptr1, ptr2); // now ptr1 -> Z2, ptr2 -> Z1

CodePudding user response：

You could do what you attempted, but using dynamically allocated arrays:

int* tmp;
int* Z1 = new int[10];
int* Z2 = new int[10];

// do something...

tmp = Z2; 
Z2 = Z1; 
Z1 = tmp;