Is there any way to test if something is null? I don't mean zero, I mean undefined. I think I read somewhere that the CS doesn't have the concept of null, but I'm not sure. Also, I'm using OBSE, if that matters.
For most variables, null is meaningless. All the default types (ref, short, long, float) are automatically initialised to 0. For ref variables, 0 is equivalent to a null, but for the others it is simply the default value. OBSE String_Vars also have a null value equivalent of 0.
Only for Array_Vars do we have an actual null, which can be tested for using Ar_Null.
To be pedantic, by the way, you don't mean "undefined" but "uninitialised" - the definition is the bit at the top of the script. In the Oblivion scripting engine, initialising takes place the first time a variable is defined in a save game. The only way to check if you haven't yet assigned a value to it is to have another variable which you set the first time you set the first variable.