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Re: The nth occurrence of a character

by mickeyn (Priest)
on Feb 08, 2006 at 15:03 UTC ( #528813=note: print w/ replies, xml ) Need Help??

in reply to The nth occurrence of a character

allow me to suggest another way that may serve you if you want to access different characters at different occurances many times:

my %hash; my @split = split //, $string; my @positions = map { [$split[$_], $_] } 1 .. @split-1; undef @split; foreach (@positions){ push @{$hash{$_->[0]}}, $_->[1]; } undef @positions ;

now, for each character you have a hash entry with all its positions in the string (array).
if for example you want to get the 3rd occurance of 'A', you will simply need to access: $hash{A}[2]
(2 will be the 3rd index in the array)

You wannted efficient function, and this way allows you to get you data in one hash+array access which IMHO is efficient.
the price you will pay is the one-time building of the hash (per string).


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