You went through a subset of the things I did to try and isolate this obfu writers dream before I gave up, posted and went to bed.

The original line of code that brought this to my attention (read:What the *&£*&"% is going on here!!!!!) had two post-incremented strings, one twice, in a double-mapped, for modified array assignment (I was generating yet another set of test data).

Needless to say, when I went and looked at the output, I was more than bemused.

The best and nicely concise explanation of the how's and why's is dws's post. Made nice reading first thing this morning, to discover I wasn't loosing my sanity (what little I have left:).

Cheers.