my $one = 1;
my $zero = 0;
my $undef;
my $result;

$result = 1;              # 1
$result = 1 || 0;         # also 1
$result = 0 || 1;         # also 1
$result = $zero || $one;  # also 1
$result = $zero // $one;  # 0
$result = $zero // 1;     # 0 as well
$result = 0 // 1;         # 0 as well
$result = $undef // $one; # 1 again
$result = $undef || $one; # 1 again

$result = fork || die;    # dies in the child process or if failing to
+ fork
$result = fork && die;    # dies in the parent process
$result = fork // die;    # dies in process unable to fork a child 
# (beware the return values of function calls, for they are subtle and
+ quick to bite your behind)

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In reply to Re^3: if defined not working by mr_mischief
in thread if defined not working by liorlew

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