what is benefit of unless ?

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Re: what is benefit of unless ? by holli (Abbot) on Feb 05, 2005 at 17:43 UTC
`$ cat input foo bar $ perl -ne 'print unless /^$/../^$/' input foo bar $ perl -ne 'print if not /^$/../^$/' input foo bar $ perl -ne 'print if ! /^$/../^$/' input foo bar` [download] The unless statement is equivalent to if not, but is different from if ! due to the associativity and precedence rules covered in perlop. A benefit of this behavior allows the reduction of runs of blank lines to a single blank line. taken from here	[reply] [d/l]
Re: what is benefit of unless ? by Anonymous Monk on Feb 05, 2005 at 12:04 UTC
You can use "else" with "unless". "unless" means "if not", so it reverses the meaning of an "if" comparison. See perlsyn for details. Please read Where should I post X? and How (Not) To Ask A Question.	[reply]
equivalent code for unless by Anonymous Monk on Feb 05, 2005 at 12:15 UTC
is this the equivalent code for " unless(condition)" ? if !(condition) { ... ... } else { ... ... } reply soon, barun parichha	[reply]
Re: equivalent code for unless by merlyn (Sage) on Feb 05, 2005 at 13:04 UTC
`unless ($boolean) { ... }` [download] is nearly completely equivalent to: `if (not $boolean) { ... }` [download] (The slight difference is in the "last expression evaluated" return value for a subroutine, but that's only a minor distracting point.) -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply] [d/l] [select]
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Re: what is benefit of unless ? by prasadbabu (Prior) on Feb 05, 2005 at 12:12 UTC
It is not similar statement. `$a = 10; print "if stmt true" if ($a == 10); print "unless" unless ($a == 10);` [download] Prasad	[reply] [d/l]