By and large, Christchurch is a very safe city.  The majority of locals are friendly, helpful and honest and like to help tourists enjoy their stay, but as with all cities, there are unsavoury types, places best avoided and precautions you should take.  New Zealand has a reputation for being a safe place to travel but don't take this as meaning you don't need to apply normal common sense.  Always lock your vehicle and take valuables with you, especially if you're travelling in a camper van.  During the day you can feel safe in pretty much any part of Christchurch.  At night however, it's best to avoid Manchester Street north of Armagh Street (frequented by prostitutes, pimps and their clients), parks and badly lit areas.  Take normal precautions in the bars, pubs and clubs in the central city and don't accept lifts from people you've just met, however friendly they are.  Buses are a safe form of transport at night but avoid walking from your bus stop to your accommodation on your own if you can.  If you experience any unwanted attention on a bus, move to a seat close to the driver and alert him/her if neccesary.  Taxis are also a safe means of transport and aren't too expensive.  If you need to report anything or require (non-urgent) Police help, there's a Police 'kiosk' in Cathedral Square.  For emergency help, dial 111.  Unless you're very unlucky and/or you take unnecessary risks, you should have a perfectly safe time in Christchurch.