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Re: Re: New perl student... feeling stupid

by Tanya (Initiate)
on May 18, 2001 at 21:32 UTC ( [id://81564]=note: print w/replies, xml ) Need Help??


in reply to Re: New perl student... feeling stupid
in thread New perl student... feeling stupid

Hrmmm I see... and I changed my code to reflect your advice.. it makes sence to me, however, now my program just hangs. It will start to run the program but there is no out put. it just sits there.

Thanks for your help by the way..

I really apreciate it.

I am really new to perl. tanya

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(arturo) Re (3) : New perl student... feeling stupid
by arturo (Vicar) on May 18, 2001 at 22:26 UTC

    the "diamond" operator <> attempts to read a line from the file whose name you pass on the command line. (e.g. ./myscript.pl file.txt) If you pass more than one filename on the command line, it will loop over all the lines in each file.

    Read up on <> in perldoc perlop

    If it runs out of command-line arguments and you try to read from it, then it attempts to read from STDIN (in this context, the keyboard). What your code is doing is reading in the file once, on the first pass. You think it's going to read it again when you say  while ( <> ) {, but what it's actually doing is attempting to read another file whose name was passed to it on the command line. But there is no such thing, so it just sits there expecting input from the keyboard (Control-D is the symbol for "end of file", so try hitting that a few times and see what happens).

    Moral of the story: don't do it that way =) Loop through the file *once* and do all your counting on that one run through it.

    HTH

    perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); +$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth +er_name\n"'

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