% perl -wle 'print 0 + $_ for qw{ 123 123foo 12e3 12e3f4 inf inflight }'
123
Argument "123foo" isn't numeric in addition (+) at -e line 1.
123
12000
Argument "12e3f4" isn't numeric in addition (+) at -e line 1.
12000
Inf
Argument "inflight" isn't numeric in addition (+) at -e line 1.
Inf
%