Sorry all should have added..

Have done the split on first field 
($tag)=split (/\|/,$data,2);

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as well as substr and index stuff 
$tag=substr ($data,0,index($data,'\|',));

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I then benchmarked them
Benchmark: timing 1000000 iterations of split, substr...
     split:  8 wallclock secs ( 6.93 usr +  0.00 sys =  6.93 CPU) @ 14
+4279.32/s(n=1000000)
    substr:  1 wallclock secs ( 1.54 usr +  0.00 sys =  1.54 CPU) @ 64
+8088.14/s(n=1000000)

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should split be slow compared to substr?
Thinking about what i really want to know monks...
Once i ahve the first field is there a quick way of spliting this field on first space then on an undersocre (if it exsits)?
In my test file I have 5161033 lines, split slows down processing dramatically. When more substr are introduced processing slows down agian!

In reply to Re: Re: Re: Re: Alternatives to split? by Perl Apprentice
in thread Alternatives to split? by Perl Apprentice

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