@ARGV in while loop

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

Dear Monks,

I may ask a stupid question, but why the $ARGV[0] in while loop cannot be accessed?

I thought @ARGV is global variable and should be accessed anywhere, of course from within of while loop.

did I miss something?

 print $ARGV[0],"\n";  #printed
  while(<>){
       print "$ARGV[0]\n"; #cannot be printed
   }
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Comment on @ARGV in while loop Download Code

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Re: @ARGV in while loop by BrowserUk (Patriarch) on Feb 14, 2014 at 17:38 UTC
why the $ARGV[0] in while loop cannot be accessed? Because the diamond operator (when used with the null filehandle `<>`) consumes the contents of `@ARGV`. See the section of perlop I/O-Operators that starts with the sentence: The null filehandle <> is special: for the details. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^2: @ARGV in while loop by lightoverhead (Pilgrim) on Feb 14, 2014 at 17:59 UTC
Thank you BrowserUK. You are right. It's good to learn. what about this: `for(;;){ print "3:\t$ARGV[0]\n"; #cannot print either last; }` [download] Is $ARGV[0] consumed too?	[reply] [d/l]
Re^3: @ARGV in while loop by lightoverhead (Pilgrim) on Feb 14, 2014 at 18:39 UTC
my fault I put for(;;;) after while(). if run for(;;) first, it will print $ARGV[0]	[reply]
Re: @ARGV in while loop by Kenosis (Priest) on Feb 14, 2014 at 17:53 UTC
However, if you want to `print` what `<>` is currently consuming, you can: `use strict; use warnings; print $ARGV[0], "\n"; #printed while (<>) { print "$ARGV\n"; #can be printed }` [download]	[reply] [d/l] [select]
Re^2: @ARGV in while loop by lightoverhead (Pilgrim) on Feb 14, 2014 at 18:02 UTC
Thank you. You are right.	[reply]


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