> $_ automatically was assigned the last line
That's a special DWIM magic within the while condition only!
while (<>) {
... which is Perl shorthand for the more explicitly written version: ...
while (defined($line = <ARGV>)) {
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[d/l]
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... but not documented under while, but in perlop under "I/O-Operators" (where the internal link anchor seems not to work)
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I've already updated an excerpt of the documentation in perlsyn, but yes perlop is indeed clearer, thanks!
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Perhaps a better thought model is that $_ gets assigned the last thing read. At the end of the file, that last thing is the EOF, which is returned as undef.
The fundamental problem here was poor loop design. The use of for(;;){} or while (1){} should be restricted to very special circumstances like an infinite loop in server code to wait for next connection, etc. If the loop is coded differently and I would argue properly, as corion suggests, while (<>){}, this handling undef inside the loop problem goes away. | [reply] |
