Print unless behaving strangely

chrisayres11 has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Print unless behaving strangely by johngg (Canon) on Jun 01, 2014 at 22:22 UTC
There could be a non-printing character before the comma that is causing your match to fail; I inserted a NULL which doesn't show up when you print the line. You can inspect each character using split along with ord and sprintf inside a map, printing the ordinal value of each using say. `$ perl -E ' $_ = qq{PID: \0, VID: 255, SN: AGM163923J5}; say; say for map {sprintf q{0x%02x}, ord } split m{};' PID: , VID: 255, SN: AGM163923J5 0x50 0x49 0x44 0x3a 0x20 0x00 <-- the unseen NULL 0x2c 0x20 0x56 0x49 0x44 0x3a 0x20 0x32 0x35 0x35 0x2c 0x20 0x53 0x4e 0x3a 0x20 0x41 0x47 0x4d 0x31 0x36 0x33 0x39 0x32 0x33 0x4a 0x35 $` [download] I hope this is helpful. Cheers, JohnGG	[reply] [d/l]
Re^2: Print unless behaving strangely by LanX (Saint) on Jun 01, 2014 at 22:59 UTC
this or any other "invisible" problem could also be visualized with Data::Dump `use Data::Dump; $_ = qq{PID: \0, VID: 255, SN: AGM163923J5}; dd $_;` [download] `"PID: \0, VID: 255, SN: AGM163923J5"` Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l] [select]
Re^3: Print unless behaving strangely by chrisayres11 (Novice) on Jun 03, 2014 at 09:26 UTC
Thanks for all the replies, I will try to answer them all Yes I did mean "$_ contains the value 'PID: , VID: 255, SN: AGM163923J5". So this wasn't a section of the perl code. I am reading a file and it is at this line that strangeness happens. Yes I am using Strict and Warnings I have put the output direct from the Cisco CLI through a Hex translator and there doesn't seem to be any hidden/null characters PID: , VID: 0x500x490x440x3a0x200x2c0x200x560x490x440x3a but the output from the file perl is holding the string in does have extra characters. 0x500x490x440x3a 0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x2c 0x560x490x440x3a Thanks for all your help	[reply]
Re: Print unless behaving strangely by Laurent_R (Canon) on Jun 01, 2014 at 22:08 UTC
To me, the regex is correct. I tried to copy and paste the exact code that you posted under the Perl debugger: `DB<1> $_ = "PID: , VID: 255, SN: AGM163923J5"; DB<2> print $_ unless /PID: ,/; DB<3>` [download] So it works as I expected (not printing $_ because of the successful match) and not as your reported result. Could it be that there are really two spaces between the colon after PID and the comma, or perhaps a tab and not a space, or some other special character? A starting point for the investigation might be to try this: `print $_ unless /PID:\s+,/;` [download] to see if it matches or not.	[reply] [d/l] [select]
Re: Print unless behaving strangely by LanX (Saint) on Jun 01, 2014 at 21:29 UTC
This `$_ = PID: , VID: 255, SN: AGM163923J5` isn't Perl code°... did you forget quotes around the string? Do you use strict and warnings ? Cheers Rolf ( addicted to the Perl Programming Language) °) or at least not the one you expect. :-)	[reply] [d/l]
Re^2: Print unless behaving strangely by boftx (Deacon) on Jun 01, 2014 at 21:48 UTC
I gave him the benefit of the doubt and assumed he was saying "$_ contains the value 'PID: , VID: 255, SN: AGM163923J5'. Here is what happens ...". Even so, this snippet works for me: `my $foo = 'PID: , VID: 255, SN: AGM163923J5'; print "NOT MATCHED!\n" unless $foo =~ /PID: ,/;` [download] It helps to remember that the primary goal is to drain the swamp even when you are hip-deep in alligators.	[reply] [d/l]
Re: Print unless behaving strangely by chrisayres11 (Novice) on Jun 03, 2014 at 10:32 UTC
Thanks for all the replies, I will try to answer them all Yes I did mean "$_ contains the value 'PID: , VID: 255, SN: AGM163923J5". So this wasn't a section of the perl code. I am reading a file and it is at this line that strangeness happens. Yes I am using Strict and Warnings I have put the output direct from the Cisco CLI through a Hex translator and there doesn't seem to be any hidden/null characters PID: , VID: 0x500x490x440x3a0x200x2c0x200x560x490x440x3a but the output from the file perl is holding the string in does have extra characters. 0x500x490x440x3a 0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x7f0x2c 0x560x490x440x3a Thanks for all your help	[reply]