[ramshorns]

That's the idiomatic way? Cool. The more straightforward-looking way,

    for(i = n-1; i >= 0; i--)
        { /* operate on a[i] */ }

breaks if i is unsigned, like a size_t.

[a1369209993]

Yep. That why it's a idiom, rather than a obvious-way-of-doing-it-that-anyone-competent-would-use.