in reply to strip multiple spaces
You have used the regex / / (match one space) as delimiter
for split. Unfortunatly the string in $line contains several
consecutive spaces, so perl does what it's told, split on one space. As an
example:
But, what if your string looked something like this: $line = " foo bar "; Using \s+ 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:
$line is assigned the string "foo..bar", where the '.' is meant to be space (it's more visible). That would output:$line = "foo bar"; print ++$i, ". $_\n" for split / /, $line;
1. foo 2. 3. barIt 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 "; Using \s+ 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:
1. foo 2. barAh, just what we want (in almost all cases I would dare to say). As an interesting note, consider the following:
Whereasperl -MO=Deparse -e 'split " "' split(/\s+/, $_, 0);
generates the exact same output - but we know that the semantics is not the same. But as long as perl does The Right Thing(TM), I'm happy :-)perl -MO=Deparse -e 'split /\s+/' split(/\s+/, $_, 0);
Autark
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