[SOLVED] 0 is false; 1 is true; What about Yes/No/Null?

[cunoodle2]

I have data that I need to store for a few different items.

 

I WAS just going to use 0 for no and 1 for yes (same as true/false) but then I realized that I also have to have an "empty" or "Null" value.

 

I can't just use 0,1 and NULL because I retrieve the intval() of the item and intval(NULL) returns 0.

 

Is there a rule/set of numbers defined for empty,no,yes?  I was going go use 0,1,2 respectively but wasn't sure if there was like a standard rule like true/false.  Anyone have any input on this?

[Ken2k7]

Let null be -1?

[haku]

I agree. If there is TRUE, FALSE and one other option, I always use -1 for the other option.

[cunoodle2]

Ok cool.  I'll follow those guidelines then.  I just want to make sure I'm conforming by standard rules and wanted to have a dead set in stone set of rules for this project.

[haku]

There unfortunately aren't a set of standard rules (or at least, I've never heard of one), rather there are just ways that most of us seem to do stuff, most of the time. But they are more unwritten rules than anything.