This is probably a dumb question, but my dad has an old 35mm Nikon SLR, which one I can't recall, but he doesn't use it anymore and I was wondering if that those lenses would work on a Nikon Digital SLR. Since I would like to buy one over the holiday (or even better find it under a christmas tree) I would like to save money if I could, and just use those lenses. Thanks a lot.
You would need to know the details of exactly which film SLR and which DSLR. In some cases the matchup would work perfectly and in other case it would absolutly not work, to the point of damaging the DSLR. The details really do matter here.
For example. All of the autofocus lens I used with my film based Nikon N90 work perfectly with my D50 DSLR. but I have some older "non-AI" lenses that were used with my Nikon F2. These work in a limited way on the N90 and can't be used at all on the D50. I have some "AI" lenses for the F2 tht work wel on the N90 and in a limited way on the D50. But if my DSLR were a D200 or a D100 then the older AI lenses would work fully - Complicated? For a beginner, Yes.
So I hate to answer "it depends" but that is the best answer. The good news is that if you can find out the details you can have a definite exact answer.
In general however, if the old lenses are manual focus they will not magically become auto focus lenses when you mount then to a new camera body. Likewise if you buy a camera body that requires electronic contacts with a lens for the body's meter to work and the lens lacks those contacts (as all manual lenses do) then the meter will not work. Some of the new bodies lack the mechanical interface and have only electronic one. OK it depends....
When you are looking at the older lenses there are several types
1) non-AI these had a little "rabbit ear" thing screwed the the aperture ring that engaged a little metal bar under the viewfinder.
2) AI and AIS, these lacked the rabbit ears and had a bit of metal milled of the aperture ring that engaged a a tab on the f-mount
3) Auto focus - gold plated electronic contacs on the backof the lens
There are sub types of the above and other types (p-type) and some older lenses may have been converted (Nikon offered this service) but you don't need to care that much. Just tell us what you've got.