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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