my $x;
if (f()) {
   ...
   $x = ...;
} else {
   ...
   $x = ...;
}

##</code><code>##

my $found;
for (...) {
   if (...) {
      $found = ...
   }
}

##</code><code>##

my @a;
while (...)
   ...
   push @a, ...;
}