Why are this pattern match failing ?

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

Dear all, I have a pattern match thats bugging me and I can't seem to figure out why it's failing. I fear the answer is embarrassing, so please go ahead and embarrass me :)
Here's part of my code:

143: if(my @d = $h->fetchrow_array()) {
144:   print STDERR "equip_id: $e_id -> ". $d[0] ." (rep_id = ". $d[1]
+ .")\n";
145:   if($d[0] eq /NA/) {
[download]

It offers this output (two examples):

equip_id: 5212 -> -NA- (rep_id = 154)
Use of uninitialized value in pattern match (m//) at test.pl line 145.

equip_id: 1337 -> 4047.3 (rep_id = 152)
Use of uninitialized value in pattern match (m//) at test.pl line 145.
[download]

What is not initialized, or why ?

Comment on Why are this pattern match failing ? Select or Download Code

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Re: Why are this pattern match failing ? by citromatik (Curate) on Apr 03, 2009 at 10:33 UTC
Did you mean...? `if ($d[0] =~ /NA/){` or `if ($d[0] eq "NA"){` Since pattern matching defaults to the `$_` variable, what you wrote is interpreted as `if($d[0] eq ($_=~/NA/)`. Probably `$_` is undefined, and that is causing the `Use of uninitialized value` message. citromatik	[reply] [d/l] [select]
Re: Why are this pattern match failing ? by jettero (Monsignor) on Apr 03, 2009 at 10:33 UTC
embarassing: `$string eq m/pattern/` not embarassing: `$string =~ m/pattern/` Oh, wait, that doesn't answer the question. :) I don't know why $d[0] is uninitialized... perhaps your database returned an undef or there were no rows to fetch, or you never did an execute. Who can tell. From the code snipped, eq vs =~ is the only real problem I can see. UPDATE: JavaFan, OIC. Yeah, I missed that. -Paul	[reply] [d/l] [select]
Re^2: Why are this pattern match failing ? by JavaFan (Canon) on Apr 03, 2009 at 10:38 UTC
`$d[0]` isn't uninitialized, but `$_` is. And that's where the pattern matches against.	[reply] [d/l] [select]
Re: Why are this pattern match failing ? by ww (Archbishop) on Apr 03, 2009 at 10:37 UTC
Blush #1: Insufficient information (for /me anyway). Blush #2: But did you (maybe) mean this? `if($d[0] =~ /NA/) {` ...or this? `if($d[0] eq 'NA') {`	[reply] [d/l] [select]
Re: Why are this pattern match failing ? by jantelar (Initiate) on Apr 03, 2009 at 10:51 UTC
blush I've been staring at that line for so long, and was unable to see the obvious. Of course I meant =~ Thanks !	[reply]
Re: Why are this pattern match failing ? by codeacrobat (Chaplain) on Apr 03, 2009 at 14:03 UTC
could have been q/NA/ ;-) `print+qq(\L@{[ref\&@]}@{['@'x7^'!#2/"!4']});`	[reply] [d/l]