while loop - How do I detect an empty line from input or a file in Perl? -


while ($_ ne ' \n') doesn't detect if input empty line , loop indeterminately in while. why?

depends mean "an empty line".

does line contain no characters other newline?

if ($_ eq "\n") # note, \n means newline in double quoted string.

or

if (/^$/)

does line contain whitespace characters

if (/^\s*$/)

but easier if invert logic line doesn't include non-whitespace characters

if (! /\s/)

one of should want.


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