Digital SLR lenses vs. Regular SLR Lenses?

I am thinking of upgrading from a 35 mm SLR to a digital SLR. I have really good lenses.(Regular which came with the Pentax , Macro and Zoom I bought , they are Sigma lenses.) I have a pentax camera and Sigma lenses. Which are working fine together.
Would the lenses I have been using fit on any digital SLR camera or do the digital cameras require different lenses. someone kind of told me that every digital camera has a differnt mount for lenses. I am asking here because I need to hear it from another source. Thanks

To my knowledge, every Pentax K-mount lens fits every Pentax K-mount camera ever made. The Pentax mount is the most backward compatible in history, even more so than the often highly acclaimed Nikon F mount.

If your lenses are older Pentax screw mount lenses, though, you'll need to purchase an inexpensive K-mount to M42 adapter. Since the K-mount was designed with this adapter in mind, there is no loss of performance or infinity focus as with many other lens mount adapters. You do, however, lose full aperture metering.

It goes without saying, though, that no manual focus lens will autofocus even on an autofocus camera, although you probably knew this. I do understand, though, that Pentax made a teleconverter than at least permits some degree of autofocusing even with manual focus lenses.

Different cameras do have different lens mounts so not all SLR lenses fit all cameras. Before you purchase a digital SLR, maybe you should take all your stuff to the camera store and ask them what might be the best route for you. Some film SLR lenses will fot onto digital SLR bodies, but there are differences in the focal length and you ahve to make some adjustments.

Sigma is a good brand and is compatible with many different SLRs. But, before you buy anything, go try them out. A good camera store should be able to help you.

As long as the lenses are auto-focus they should work on your new DSLR. Digital cameras don't require digital lenses. You just get light cutoff if you try to use digital lenses on film cameras

All things being equal Nikon for Nikon, Canon for Canon, Pentax for Pentax.

if you are using an automatic pentax like mz60 then your lens woth mount onto the digi Pentax DSLR, If you are using an older pentax like K1000 (manual focus) these lens wont fit new pentax DSLR.

as other say Canon 4 Canon, Pentax for Pentax etc

Well, to my knowledge, using film lenses on a digital camera will allow you to take advantage of the "sweet spot" in the center of the lens. This occurs because the lens was made to cover the full size of the 35 film. The sensor in most digital cameras is smaller than this, thus you get the "sweet spot" as it were.

Pentax Lens will be the best than Sigma Lens,digital SLR will goes for DSLR Lenses and not for SLR lenses,unless you buy /change to Canon Camera DSLR then you could use back the same Canon SLR lenses.