Dogs, or more accurately dog owners, are regulated at three different levels:
Animal welfare is regulated largely at the federal level - the owner education requirements, the ban on docking and cropping, microchipping - these are all federal laws.
Dog control is the competency of the various cantons, and each canton has it's own regulations. You must follow not only the regulations of your canton or residence, but also those of any canton you visit.
Cantonal regs vary widely, from rather laissez-faire (ZG) to draconian BSL (ZH, GE, VS are examples.) About half the cantons have some form of BSL in place, either banning or restricting certain breeds. In some cantons the size of the dog might trigger additional regulation, in some the number of dogs in the household.
Note especially that some cantons' education requirements (for some breeds or sizes) go beyond the federal SKN course. ZH is one of those, by the way. Any dog whose adult size is expected to be over 45cm or 15kg falls under the List 1 training requirements.
You can find a summary of the various cantonal regs here, from the Tier Im Recht foundation: http://www.tierimrecht.org/de/tiersc...echt/index.php
For canton ZH, the summary is here: http://www.tierimrecht.org/de/tiersc...ht/zuerich.php
Please read also the ZH Verhaltenskodex for Hundehalter, given in the link Lorena provided. This gives you an idea of attitudes in canton ZH, make sure you understand what is expected of you.
Also note that at the top of each canton's page of the TIR summary is a link to the actual text of the law. Read it!
A third level of control is at the Gemeinde - you need to understand where dogs are allowed, where they are banned. You need to understand where they are restricted to on-lead, where they are allowed to run free. (SZ is the only canton with a general leash law in public.) You need to understand night time restrictions, quiet hour restrictions, pick up requirements - and the fines for breaking any of these. Also you need to understand the dog tax.
There might be a fourth level of control - your building or neighborhood. Check with your landlord, with the neighborhood association for further regulations.
And even a fifth level of control - your neighbors. Nachbarrecht means that your neighbors' views need to be taken into account, compromises need to be sought, harmony needs to be a priority - as all too often neighbors are able to force families to get rid of their dogs.
If you happen to have dog friendly neighbors you might never notice this. If one of your neighbors is not a dog lover, though, your life might turn into a living hell.
Similarly attitudes to enforcement of existing laws varies widely. Some cantons/communities have laws on the books that are never enforced. Or some have laws that are enforced against you, but not your well-connected neighbor.
Take for instance the federal SKN requirements. In my community this is taken seriously, I must give the Gemeinde a copy of each dog's SKN certificate - and they will chase scofflaws down for it. Yet other posters report that their communities turn a blind eye to the law. Some communities check your SKN status when you are brought up on another charge, and only then fine the scofflaws.
All of this is a long-winded way of saying that while our varying experiences might give you a hint of what your life would be like with a dog, you cannot assume that other people's experiences will be anything like yours.
I live in a community that is becoming more and more anti-dog. Neighborhood mobbing is not uncommon, a dog owner needs first and foremost to know and follow all laws and to respect local etiquette in order to get along with the neighbors to be able to give one's dog a good life.
(And a dog owner needs to have a rather thick skin, and be able to quote article and paragraph to Hans Ueli Hundehasser.)
We had a wave of poisonings this last summer, the danger is such that most area dog schools have added 'Anti-Giftköder' training to their curricula.
Even if there wasn't a leash law I would not let my dogs off lead in our area as the chance of their being hurt by some angry idiot is too great.
Although a few restaurants still allow dogs I would never take mine, as the risk of another patron being offended is too great.
A sad sign of the times - but this is a good example of local attitudes. Too many people here do seem to think 'If I don't like it, no one else should have it'. This goes for dogs, and pretty much everything else.
Now - the next poster will likely come along and describe their Swiss dog owner experience as canine heaven.
Both are valid.
As with absolutely everything in Switzerland - local attitudes set the tone and thus the law and it's enforcement (or lack of enforcement) and those local attitudes vary widely.
But the one thing that remains pretty much the same across Switzerland is the difficulty of finding responsible, qualifed dog care. So make that a priority as you start out.
Since everything is local, the best way to get a picture of dog ownership would be to talk to the folks you see walking their dogs in your neighborhood.
Wishing you and yoru future four legged friend all the best