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Re^2: If conditional checks

by kitkit201 (Initiate)
on Dec 09, 2012 at 05:14 UTC ( #1007952=note: print w/ replies, xml ) Need Help??


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

Thanks Superdoc, but I dont have perl 5.10 installed on my production system. is there any other way to do it? without the smart operator


Comment on Re^2: If conditional checks
Re^3: If conditional checks
by Kenosis (Priest) on Dec 09, 2012 at 05:45 UTC

    You can use grep instead of the smart match operator (~~):

    ... if ( grep /^$host$/, @redAlert or ( grep /^$host$/, @orangeAlert and $statusHist01 == 2 ) or $statusHistTot == 3 ) { print "We've got a winner!"; } ...

    grep iterates through all array elements, and in scalar context (as in this case), it returns the number of times an expression is true. Each expression in the greps is a regex that requires an exact match between the value of $host and an array element (contained in the default scalar, $_) to be evaluated as true.

      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

        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.

Re^3: If conditional checks
by tobyink (Abbot) on Dec 09, 2012 at 11:06 UTC

    If you don't have Perl 5.10, you could try Perl 5.12, or Perl 5.14, or Perl 5.16. Or wait 6 months and try Perl 5.18.

    perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

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