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Re^3: Prime Number Finder

by chith (Initiate)
on Jan 20, 2013 at 19:45 UTC ( #1014325=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Prime Number Finder
in thread Prime Number Finder

this is the actual code which works for windows

#!usr/bin/perl -w use strict; use warnings; my $o = 2; print "enter upto what number you wish to generate the primes: "; my $e = <STDIN>; my ($i,$j,$p); my @prime_=(); print "prime numbers are:\n"; for($i=$o; $i<=$e; $i++) { $p=0; for($j=1; $j<=$i; $j++) { if($i % $j== 0) { $prime_[$p] = "$j"; $p++; } if ($prime_[1] == $i) { print "$i\t"; } } } print"\n";


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Re^4: Prime Number Finder
by Anonymous Monk on Sep 17, 2013 at 08:46 UTC
    This code is quite fast, since it skips a lot of unnecessary operations
    #!/usr/bin/perl use strict; use warnings; use POSIX; my ($i,$j,$h,$sentinel) = (0,0,0,0); # i>=3 for($i=1000000000; $i<=1000000500; $i++){ # if $i is an even number, it can't be a prime if($i%2==0){} else{ $h=POSIX::floor(sqrt($i)); $sentinel=0; # since $i can't be even -> only divide by odd numbers for($j=3; $j<=$h; $j+=2){ if($i%$j==0){ $sentinel++; # $i is not a prime, we can get out of the loop $j=$h; } } if($sentinel==0){ print "$i \n"; } } }

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