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in reply to Re: question about $_ and eof
in thread question about $_ and eof

Just to clarify one point about 

while (<STDIN>)

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Q: Why does this not stop on a blank line?

A: <STDIN> is returning a newline character '\n', which is true. In practice, regardless of O/S, you never get the empty string or a bare 0, hence the only false value you encounter is undef.

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Re: Re: Re: question about $_ and eof
by strat (Canon) on Mar 13, 2002 at 12:36 UTC
    > A: <STDIN> is returning a newline character '\n', which
    > is true. In practice, regardless of O/S, you never get
    > the empty string or a bare 0, hence the only false value
    > you encounter is undef.

    I think, the construct while (<STDIN>) { is just another way to write:  while (defined ($_ = <STDIN>)){, not only for while ($_ = <STDIN>) {.

    The difference is not big; only if there is a 0 (=zero) on the last line of a file without \n, it can become essential. But with pure STDIN this case might never happen, only with files or the like...

    Best regards,
    perl -le "s==*F=e=>y~\*martinF~stronat~=>s~[^\w]~~g=>chop,print"

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