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perl if-then-else logic and how to handle no data if regex doesn't match

Answer 1

+8 A:

Set a boolean to false.
Inside the while loop, if the regex matches, set the boolean to true.
Outside the while loop, if the boolean is still false, print NOTHING TO REPORT.

mcandre 2010-07-06 19:22:03

Thanks for the helping me with this logic.

jda6one9 2010-07-06 23:36:43

I use this pattern all the time :)

mcandre 2010-07-07 13:13:37

Answer 2

A:

I don't think, I'm getting this right. I tried as suggested (@mcandre) and placed outside of the while loop and still getting the same behavior. Where should I place this check?

use strict;
use warnings;
my($mon,$day,$year,$file) = @ARGV;
my $boolean = 0;
splice(@ARGV, 0, 4, ());            
foreach my $server ( @ARGV ) {      
    print "========================================================================\n";
    print "REPORTING SUMMARY for BACKUP SERVER : $server\n"; 
    open(my $fh,"ssh $server cat $file |") or die "can't open log $server:$file: $!\n";
    while (my $line = <$fh>) {
        if ($line =~ m/.* $mon $day \d{2}:\d{2}:\d{2} $year:.*(host=|ERROR:|backup-date=|backup-size=|backup-time=|backup-status)/) {
            print $line;
            $boolean=1; #set to true
            #print "Boolean is set to $boolean \n";
        }
    } #end while loop
        if ($boolean=0) {
           print "Boolean is set to $boolean \n";
           print "NOTHING TO REPORT FOR THIS DATE... \n";
        }
    close($fh);
}

jda6one9 2010-07-06 22:51:29

@jaedre619: In `if ($boolean=0)`, you're assigning 0 to `$boolean`. You want `if ($boolean == 0)`. You also want to reset `$boolean` back to 0 inside your `foreach` loop, probably. Also you should rename `$boolean` to something meaningful, like `$has_data`.

indiv 2010-07-06 22:59:05

Also, you're using strict and warnings, so you should have seen something like this when you compiled and ran it: `Found = in conditional, should be == at...`. Don't ignore those warnings, they tell you something is wrong.

indiv 2010-07-06 23:08:12

@indiv: Thank you!! It know works, as I would like it too...Also, I did not ignore warning. I would have tried to resolve that. Thanks.

jda6one9 2010-07-06 23:19:12

Answer 3

+1 A:

This works now:

use strict;
use warnings;
my($mon,$day,$year,$file) = @ARGV;
my $has_data = 0;
splice(@ARGV, 0, 4, ());            
foreach my $server ( @ARGV ) {     
    print "========================================================================\n";
    print "REPORTING SUMMARY for BACKUP SERVER : $server\n";
    open(my $fh,"ssh $server cat $file |") or die "can't open log $server:$file: $!\n";
    while (my $line = <$fh>) {
        if ($line =~ m/.* $mon $day \d{2}:\d{2}:\d{2} $year:.*(host=|ERROR:|backup-date=|backup-size=|backup-time=|backup-status)/) {
            print $line;
            $has_data=1; #set to true
            #print "Boolean is set to $has_data \n";
        }
    } #end while loop
        if ($has_data==0) {
           print "Boolean is set to $has_data \n";
           print "NOTHING TO REPORT FOR THIS DATE... \n";
        }
       $has_data=0;
       print "Boolean is reset to $has_data \n";
    close($fh);
}

jda6one9 2010-07-06 23:21:45

you don't need to reset the `$has_data=0;` at the end, since you don't use it anymore, if anything you can `undef $has_data`. Also `if ($has_data==0)` can just become `if ($has_data)`.

vol7ron 2010-07-07 05:21:43

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perl if-then-else logic and how to handle no data if regex doesn't match

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