$foo is undef SV = NULL(0x0) at 0x1275f40 REFCNT = 1 FLAGS = () Use of uninitialized value $foo in string eq at mytest.pl line 17. Use of uninitialized value $foo in string eq at mytest.pl line 17. $foo eq $foo: $foo is stringwise equal SV = PV(0x1252e70) at 0x12a0470 REFCNT = 1 FLAGS = () PV = 0 Use of uninitialized value $foo in numeric eq (==) at mytest.pl line 24. Use of uninitialized value $foo in numeric eq (==) at mytest.pl line 24. $foo == $foo: $foo is numerically equal SV = PVNV(0x12510f0) at 0x12a0608 REFCNT = 1 FLAGS = () IV = 0 NV = 0 PV = 0