| Language | null | true | false |
|---|---|---|---|
| Java | null | true | false |
| Python | None | True | False |
| Objective-C | nil, or NULL, or [NSNull null], depending on context |
YES | NO |
| C | NULL | anything except 0 | 0 |
| Lisp | NIL | T | NIL |
Objective-C is psychotic. It’s a Smalltalk dialect built on top of C (and for the most part, it got the good bits of both and left out the bad bits). Obj-C lets you instantiate arrays like [NSArray arrayWithObjects:@"Hello", @"World", nil], using nil as an end-of-array marker because C’s varargs implementation doesn’t know how many args you passed. So it has this extra “null” object that’s not really null.