comment on

how about this approach:

# ASSUME: words are sorted lexically ascending.

use warnings;
use strict;


my $last_anchor = qr{ \z \A }xms;  # init to never-matching pattern

my $first   = qr{ [A-Za-z] }xms;
my $anchor  = qr{ $first [AEIOUaeiou] }xms;
my $letters = qr{ [_A-Za-z] }xms;

my $sequence_number_field = qr{ \d+ : [ ]{4} }xms;


WORD:
while (<DATA>) {
    
    next WORD 
        unless m{ $sequence_number_field
                  (?! $last_anchor)    # NO match to last anchor
                  ($anchor $letters*)  # capture anchoring word to $1
                }xms;

    my $word = $1;
    
    $last_anchor = qr{ @{[ substr $word, 0, 2 ]} }xms;
    
    print "$word: $_";
    
    }


__DATA__
      1:    xxAardvark            <-- first if really Aardvark
      2:    Abacus
      3:    Actuary
      4:    Additive
      5:    Aeolian             <-- first if no Aardvark
   1930:    Nails               <-- #Na here
   1931:    Naked
   1932:    Name     
   1933:    Napkin   
   1934:    Narcotics
   1935:    Narrow
   1936:    Nature
   1937:    Nausea
   1938:    Navel
   1939:    Navy
   1940:    Nazi
   1941:    Nearsighted         <-- #Ne here
   1942:    Neck
   1943:    Necklace
   1944:    Necktie
   1945:    Necromancer
   1946:    Need
   1947:    Needle   
   1948:    Negligee
   1949:    Neighbour
   1950:    Neighbourhood
   1951:    Nephew
   1952:    Neptune
   1953:    Nerd
   1954:    Nervous_Breakdown
   1955:    Nest     
   1956:    Net      
   1957:    Nettles  
   1958:    New   
   1962:    New_Year
   1959:    News  
   1960:    Newspaper
   1961:    Newspaper_Reporter
   1963:    Nickname            <-- #Ni here
   1964:    Niece
   1965:    Night
   1966:    Nightclub
   1967:    Nightgown
   1969:    Nightingale
   1968:    Nightmare
   1970:    Ninepins 
   1971:    Nipples  
   1972:    Nobility            <-- #No here
   1973:    Noise  
   1974:    Noodles
   1975:    Noose  
   1976:    North
   1977:    Northern_Lights  
   1978:    Nose
   1979:    Notary
   1980:    Notebook
   1981:    November
   1982:    Nuclear_Bomb        <-- #Nu here
   1984:    Numbers
   1983:    Numbness 
   1985:    Nuns   
   1986:    Nuptial
   1987:    Nurse
   1988:    Nursing
   1989:    Nuts 
   1990:    Nymph
[download]

In reply to Re: Programatically detecting a change in letters by Anonymous Monk
in thread Programatically detecting a change in letters by hacker

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