If a line does not contain DosID= then the short circuit means that the increment on $count never occurs so the skip alternation will breakdown

But the original poster said "I am only interested in every second occurence" so I deliberately wrote it that way - counting occurrences _not_ lines.

The original logic looked at even index elements, this looks a odd ones

Yep. There's a difference. Mine looks at "every second occurence" as requested (i.e. it skips the first and displays the second and so on). If that's wrong then you fix it by changing the postincrement to preincrement.

And why did you hide your text?