Pointer assignment versus pointer arithmetic

Question

I'm working with a data set that varies in size from potentially very small, to as large as hundreds of millions.

When working with a contiguous data set, is there any difference in functionality or performance when assigning a new value to a pointer versus using pointer arithmetic to progress to my desired location?

For example, when progressing to the next member of the data, I could simply increment my pointer by one, or assign my working pointer to that memory address (assuming I already had it for whatever reason).

Operating under Windows using Visual Studio 2012 as a compiler.

Is there a predictable pattern in which you will be accessing members of this data structure, or is going to be completely random access? — Alex
– Alex, Commented Mar 19, 2013 at 2:51
It is split into blocks of predictable data, but the distances between the blocks is not always the same. So, a little bit of both. — Evan
– Evan, Commented Mar 19, 2013 at 2:53

Jacob Parker · Accepted Answer · 2013-03-19 02:52:58Z

2

As for performance, according to Andrei Alexandrescu recently (see this link, there is a link to a video of a good talk he gave there) you should prefer indexing into an array over pointer arithmetic for contiguous accesses on modern machines.

However, there is one timeless rule for optimization: measure it! :)

Without more information I have nothing to say re: differences in functionality other than "no".

edited Mar 19, 2013 at 2:52

answered Mar 19, 2013 at 2:44

Jacob Parker

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