Why are using (?:)?

The "?:" reduces the parens effect to grouping. That means, the content of the parens will not be captured to populate a $< digit> variable ($1, $2, $3, ...). It is good practice to state exactly what is meant; and if you want to just group alternatives, then (?:) is the fitting expression.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re^3: Regular Expression - delimiter/spaces problem by shmem
in thread Regular Expression - delimiter/spaces problem by demichi

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