in reply to Re^5: printing unitialized value of the 'do BLOCK'
in thread printing unitialized value of the 'do BLOCK'

There's no negation anywhere in that code. $x IS the last expression evaluated when $x is true.

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Re^7: printing unitialized value of the 'do BLOCK'
by rsFalse (Chaplain) on Dec 18, 2019 at 22:50 UTC
    Thanks for pointing this out!
    I haven't tested much, only tested with plain '1'.
    my $x = 1;

print "[$_]" for
    do{ unless( $x ){ 5 } },
    do{ unless( 1  ){ 6 } },
    ;

    [download]
    Output: 
    [1]
[]

    [download]
[reply]
[d/l]
[select]
      I'm getting [1][1] from the above code. What version of perl do you run?
      map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]
[reply]
[d/l]
[select]
        $ for v in 30 28 26 24 22 20 18 16 14 12 10; do
   printf '5.%s: ' $v
   5.${v}t/bin/perl a.pl
done
5.30: [1][1]
5.28: -bash: 5.28t/bin/perl: No such file or directory
5.26: [1][1]
5.24: [1][1]
5.22: [1][]
5.20: [1][]
5.18: [1][]
5.16: [1][]
5.14: [1][]
5.12: [1][]
5.10: [1][]

        [download]

        I think it's an unintentional change that resulted from fixing this.

[reply]
[d/l]

      And there we go. The reason the value is only defined when the last statement is an expression.

[reply]
        I thought that '1' is also expression.
[reply]

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