Here's my shot at it:

use strict;

my @list=('xxxxxa : yyyyy blah blah','xxxxxb : yyyyy blah blah','   ',
+'xxxxxc : yyyyy blah blah',': this is strange','xxxxxd : yyyyy blah b
+lah',"\n",'xxxxxe : yyyyy blah blah');

my @result = map {m/(.*?)\s+:/} @list;

print join("\n",@result);
[download]

It throws out blank lines, lines with only a trailing newline and lines which start with a colon.

The operative part counts 24 characters.

CountZero

Update:Added ? to make the match non-greedy (see blokhead's remarks)

Update 2:The operative part could be written as
map/(.*?)\s+:/,@list
and is then only 20 characters long.

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law

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