If you are running Perl 5.6.0 or better, the use warnings pragma allows fine control of what warning are produced. See perllexwarn for more details.
{
no warnings; # temporarily turn off warnings
$a = $b + $c; # I know these might be undef
}If you have an older version of Perl, the $^W variable (documented
in perlvar) controls runtime warnings for a block:
{
local $^W = 0; # temporarily turn off warnings
$a = $b + $c; # I know these might be undef
}Note that like all the punctuation variables, you cannot currently
use my() on $^W, only local().