Thread: Swapping pointers

I agree with using the variable names in the function prototypes. It certainly makes the code easier to understand.

Originally Posted by iMalc

I realise that this is a cut down piece of code, but if you're doing this here, you're almost certainly doing it in your main code.
The issue is that you should pretty much never dynamically create a vector. Think of a vector as a pointer to an array. Why would you dynamically allocate that pointer itself?! (okay it's actually typically 3 pointers but no diff)
The array inside the vector is already dynamically allocated. Then to pass them to another function, you do so by reference (const if that function doesn't modify them)

Here's a corrected and simplified version of your sample program:

Code:

snip

I could tell you why your original version didn't work, but that would probably lead you furthur away from how it should be implemented.

I almost asked about dynamically creating vectors in my original question, because it didn't seem right. The first draft of my program used references instead of pointers, but the swapping of vectors seemed slow (however, I wasn't using the swap() member function ... I'll try that now). In my actual program, the class can be rather large, and the vector can also be quite big (somewhere in the hundreds). I'm also calling "function()" many, many times. My thinking was that the swapping of pointers would mean exchanging an extremely small value, rather than a gigantic vector of stuff. Is my thinking way off? If so, why?