You have used the regex / /
(match one space) as delimiter
for split. Unfortunatly the string in $line
consecutive spaces, so perl does what it's told, split on one space. As an
$line = "foo bar";
print ++$i, ". $_\n" for split / /, $line;
is assigned the string "foo..bar"
, where the
'.' is meant to be space (it's more visible). That would output:
It prints out three lines, one which is empty (because there is
nothing between the two spaces). So we have to deal with more than
one whitespace. We could do this:
split /\s+/, $line
Now, perl will look for 1 or more spaces when trying to figure out
where to split - and in your example that would probabely work out
just fine. (don't use \s*
as delimiter as that would match everywhere)
But, what if your string looked something like this:
$line = " foo bar ";
as delimiter now would garble things up again.
It would return an extra element (which is empty) at the front.
How do we fix this then ? Well, the solution may look at bit counterintuitive
from what we have learned so far:
split " ", $line
Hm, wouldn't that just match one single space again ? Well, it should,
but it doesn't. This is a special case in perl, and if we apply
that to our test case we will get the following result:
Ah, just what we want (in almost all cases I would dare to say).
As an interesting note, consider the following:
perl -MO=Deparse -e 'split " "'
split(/\s+/, $_, 0);
perl -MO=Deparse -e 'split /\s+/'
split(/\s+/, $_, 0);
generates the exact same output - but we know
the semantics is not
the same. But as long as perl
does The Right Thing(TM), I'm happy :-)
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