... what is the index of the first non-space character? 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = '    a     ';
 ;;
 $s =~ m{ \S }xms;
 print $-[0];
"
4

[download]

... as long as it didn't invoke the regex engine.

What's the point of that?

Update: More generally: 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = 'xyzzyBARxkcdFOOyz';
 ;;
 my $vowel = qr{ [AEIOUaeiou] }xms;
 ;;
 print qq{offset of first vowel: }, $s =~ m{ ($vowel) }xms ? $-[1] : '
+none';
 ;;
 print qq{offset of last vowel: }, $s =~ m{ .* ($vowel) }xms ? $-[1] :
+ 'none';
 ;;
 print qq{offset of first vowel: }, 'XYZ' =~ m{ ($vowel) }xms ? $-[1] 
+: 'none';
"
offset of first vowel: 6
offset of last vowel: 14
offset of first vowel: none

[download]
See  @- @+ in perlvar.

Give a man a fish:  <%-{-{-{-<

In reply to Re: opposite of index+rindex? How-to? Needed? (updated) by AnomalousMonk
in thread opposite of index+rindex? How-to? Needed? by perl-diddler

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