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RE: Re: Using variables with tr///

by DrManhattan (Chaplain)
on Jul 17, 2000 at 19:59 UTC ( #22856=note: print w/replies, xml ) Need Help??


in reply to Re: Using variables with tr///
in thread Using variables with tr///

This is significantly faster than using eval:

sub count { my ($string, $char) = @_; my $index = -1; my $count = -1; do { $count++; $index = index($string, $char, $index + 1); } while ($index != -1); return $count; }

And this is faster still:

sub count { my ($string, $char) = @_; $string =~ s/[^$char]//g; return length($string); }
Eval: 56 wallclock secs (45.19 usr + 0.00 sys = 45.19 CPU) @ +3319.32/s (n=150000) While Loop: 5 wallclock secs ( 4.69 usr + 0.00 sys = 4.69 CPU) @ +31982.94/s (n=150000) Substitution: 1 wallclock secs ( 1.41 usr + 0.00 sys = 1.41 CPU) @ +106382.98/s (n=150000)

Update (7/19/00): Oh, duh. s/// returns a count of the number of changes made. Here's a faster way to write the subroutine:

sub count { my ($string, $char) = @_; return ($string =~ s/$char//g); }

- Matt

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