There are a lot of problems. You read multiple lines from the file, you close() inside the while() loop, .... Here's what you want: 
  while (<INPUT>) {
    $n++ if /^Algorithm/;
    last if /^Experiment Name/;
  }
  close INPUT;

[download]
Cheers;

Nat

In reply to Re: Counting occurances of a pattern in a file by gnat
in thread Counting occurances of a pattern in a file by MadraghRua

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