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Re^4: If conditional checks

by kitkit201 (Initiate)
on Dec 12, 2012 at 20:13 UTC ( #1008582=note: print w/ replies, xml ) Need Help??


in reply to Re^3: If conditional checks
in thread If conditional checks

Thank you for the comment. One more thing about this is the host string. I see the host scalar to only work on the hostname if it only with db, but no other characters behind it, like db4323, how would you include it to have any other characters like periods and numbers, behind it? some example hostnames would be dbwindows822.tp.com db726.tp.com


Comment on Re^4: If conditional checks
Re^5: If conditional checks
by Kenosis (Priest) on Dec 12, 2012 at 21:46 UTC

    You're most welcome!

    Here's the regex in the grep (with two added features that should be there):

    /^\Q$host\E$/; ^ ^ ^^ | | || | | |+ - End of line | | + - End quote metacharacters | + - Begin quote metacharacters (e.g., [.*\+], etc.) + - Match beginning at the start of the line

    If you remove the trailing $, it'll match a host name beginning with "db". Try the following with and without the trailing $ in the regex:

    use warnings; use strict; my $host = 'db'; while (<DATA>) { print if /^\Q$host\E$/i; } __DATA__ db db4323 dbwindows822.tp.com db726.tp.com

    Output with $:

    db

    This is because if forces an exact match, like $host eq 'db'.

    Output without $:

    db db4323 dbwindows822.tp.com db726.tp.com

    This is becuase it's only matching the first two characters of $_ (the default scalar) against the value of $host.

    Note that there's the i modifier at the end of the regex. This makes the match case-insensitive, in case you have a host like DB4323.

      Hi Kenosis, So here is the code that I have that is not working with what you did, maybe it's just me being silly again..
      #!/usr/local/bin/perl use strict; use warnings; use List::Util qw/sum/; my $host = 'db201.tp.mud'; my @redAlert = ("db"); my @orangeAlert = ( "c", "sm" ); my %status = ( 'status_history' => { 'status' => [ 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 ] + } ); my $statusHist01 = sum @{ $status{status_history}{status} }[ 0 .. 1 + ]; my $statusHistTot = sum @{ $status{status_history}{status} }; if ( grep /^\Q$host\E/i, @redAlert or ( grep /^$host/i, @orangeAlert and $statusHist01 == 2 ) or $statusHistTot == 3 ) { print "We've got a winner!"; }

        Ah! We just need to do something a little different with the partial match:

        #!/usr/local/bin/perl use strict; use warnings; use List::Util qw/sum/; my $host = 'db201.tp.mud'; my @redAlert = ("db"); my @orangeAlert = ( "c", "sm" ); my %status = ( 'status_history' => { 'status' => [ 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 ] + } ); my $statusHist01 = sum @{ $status{status_history}{status} }[ 0 .. 1 ] +; my $statusHistTot = sum @{ $status{status_history}{status} }; if ( grep $host =~ /^$_/i, @redAlert or ( grep $host =~ /^$_/i, @orangeAlert and $statusHist01 == 2 ) or $statusHistTot == 3 ) { print "We've got a winner!"; }

        The earlier grep worked because we were looking for an exact match. In this case, however, we want a partial match of the alert elements with the host. Also, since the alerts don't contain any 'special' characters, escaping isn't necessary.

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