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Re: If statement not working

by perlfan (Vicar)
on Jun 25, 2020 at 17:39 UTC ( #11118543=note: print w/replies, xml ) Need Help??


in reply to If statement not working

if ($_ = (m/^[\$]\w/)) {

Solution pointed out below. This is an assignment (using =) clobbering $_ with an empty array the true/false result. An assignment of an undefined thing evaluates to false every time. Similar to if ($_ = ()) or if ($_ = undef).

Update - because I was curious:

perl -MO=Deparse,-P -e 'if($_ = (m/foo/)) { print 'hi' }' if ($_ = /foo/) { print hi $_; } -e syntax OK

A little more insight.

update 2- corrected ty

Replies are listed 'Best First'.
Re^2: If statement not working
by AnomalousMonk (Bishop) on Jun 25, 2020 at 18:44 UTC
    This is an assignment (using =) clobbering $_ with an empty array. An assignment of an undefined ... Similar to if ($_ = ()) or if ($_ = undef).

    $_ is clobbered with the true/false result of evaluating the match of the regex against $_:

    c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -e "print 'Enter a string and I will determine the data type: '; chomp($_ = <STDIN>); dd 'A:', $_; ;; if ($_ = (m/^[\$]\w/)) { print qq{\n'$_' is a scalar data type\n}; } dd 'B:', $_; ;; if ($_ = (m/^[\@]\w/)) { print qq{\n'$_' is an array data type\n}; } dd 'C:', $_; " Enter a string and I will determine the data type: $scalar ("A:", "\$scalar") '1' is a scalar data type ("B:", 1) ("C:", "") c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -e "print 'Enter a string and I will determine the data type: '; chomp($_ = <STDIN>); dd 'A:', $_; ;; if ($_ = (m/^[\$]\w/)) { print qq{\n'$_' is a scalar data type\n}; } dd 'B:', $_; ;; if ($_ = (m/^[\@]\w/)) { print qq{\n'$_' is an array data type\n}; } dd 'C:', $_; " Enter a string and I will determine the data type: @ra ("A:", "\@ra") ("B:", "") ("C:", "")


    Give a man a fish:  <%-{-{-{-<

      ty fixed

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