Re: Newbie: parentheses, map, etc.

my @output = map s/(.*)/ $1\n/, @small_files;

The substitution operator s returns the number of captured substrings, which is 1. It also alters the string it is bound to ($_ by default, as you are aware), but this alteration is by side-effect. Check the contents of @small_files immediately after this statement.

What you want is

my @output = map " $_\n", @small_files;

Updated: I am taking the liberty of deleting the false part of my original answer (which is accurately quoted and accurately corrected in kyle's reply below). Thanks, kyle. What was I thinking?

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Re^2: Newbie: parentheses, map, etc. by kyle (Abbot) on Mar 04, 2008 at 03:47 UTC
The substitution operator s returns the list of captured substrings or, in scalar context, the number of captured substrings, which is 1. This isn't true. `s///` always returns the number of substitutions made or the empty string if no substitutions were made (see perlop). The expression in map is in list context.	[reply] [d/l]
Re^3: Newbie: parentheses, map, etc. by ysth (Canon) on Mar 04, 2008 at 06:49 UTC
The documentation lies. On failure, it returns the canonical false value, which is an empty string in string context and 0 in numeric context. -- Online Fortune Cookie Search	[reply]
Re^4: Newbie: parentheses, map, etc. by kyle (Abbot) on Mar 04, 2008 at 15:59 UTC
Upon first reading this, I thought, "what's the difference?" More to the point, "how does one behave differently from the other?" After all, an empty string in a numeric context is zero anyway. How would one ever see the difference? Some time later, the answer popped into my head. A string turned number will trigger warnings, but `s///` won't. I verified this in the Test::More fashion. Read more... (1008 Bytes) Thanks for the food for thought.	[reply] [d/l] [select]