Hi davido

well it was in June, below what I found on my disk:

There is an "X" in the middle of a 52MB string of repeated alphabet letters ($pattern = join "","a".."z")

Depending if you look for "Xabc..xyz" or "abc...xyzX" the different approaches show their strength.

I did more tests which I can't find anymore strongly indicating that index doesn't use Boyer-Moore.

Just vary the position of the "X". I'd be glad if you looked it over. :)

use Time::HiRes qw[ time ];
 
 
my $pattern = join "","a".."z";
 
my $str= $pattern x 1E6 . "X" .$pattern x1E6;
$\="\n";
$|=1;
 
print "Length: ",length $str;
 
print "\n---End X";
 
$start=time;
print "Match: ", $str =~/${pattern}X/;
printf "\t took %.3f sec\n",time-$start;
 
$start=time;
print "Index: ", index $str , "${pattern}X";
printf "\t took %.3f sec\n",time-$start;
 
print "\n---Start X";
 
$start=time;
print "Match: ", $str =~/X${pattern}/;
printf "\t took %.3f sec\n",time-$start;
 
$start=time;
print "Index: ", index $str , "X${pattern}";
printf "\t took %.3f sec\n",time-$start;

[download]

RESULT:

Length: 52000001
 
---End X
Match: 1
     took 0.021 sec
Index: 25999974
     took 0.263 sec
 
---Start X
Match: 1
     took 0.165 sec
Index: 26000000
     took 0.094 sec

[download]

Cheers Rolf

In reply to Re^4: How Index function works?? by LanX
in thread How Index function works?? by saranrsm

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