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.NET Forum / Languages / C# / September 2007Is there a free world cities DB?
Hi all, I'm looking for a free world cities data base that includes: Longitude, latitude and time zone. Thanks, Sharon. Sharon, You can probably get the latitude and longitude using Google Maps or Live Search (I know that Live Search has a web service you can perform a search on, and it will return lat/long coordinates in return). You will have to go to another service to get time zone information though.  Signature- Nicholas Paldino [.NET/C# MVP] - mvp@spam.guard.caspershouse.com > Hi all, > I'm looking for a free world cities data base that includes: > Longitude, latitude and time zone. > Thanks, > Sharon. Thanks for the reply. I'll try it. > Sharon, > [quoted text clipped - 10 lines] >> Thanks, >> Sharon. > I'm looking for a free world cities data base that includes: > Longitude, latitude and time zone. http://www.google.co.uk/search?hl=en&rlz=1T4GGIH_en-GBGB220GB220&q=world+cities+ database+free&meta= SignatureMark Rae ASP.NET MVP http://www.markrae.net Hey Mark, I did a Google search, as I always do, before posting this question. None of the free DB's offer a time zone field. I haven't even found a commercial one with this field. Sharon. >> I'm looking for a free world cities data base that includes: >> Longitude, latitude and time zone. > > http://www.google.co.uk/search?hl=en&rlz=1T4GGIH_en-GBGB220GB220&q=world+cities+ database+free&meta= You could construct this using information from various WebPages. E.G. File 1: get a list of the tz zones: http://en.wikipedia.org/wiki/List_of_tz_zones_by_country (or download the source of this (see http://en.wikipedia.org/wiki/Tz_database). File 2: find a list of cities with their long/latitudes: e.g. http://www.realestate3d.com/gps/world-latlong.htm File 3: find the current times of some world cities. E.G. http://www.timeanddate.com/worldclock/full.html?sort=2 Extract the information from these WebPages (save the HTML source, write a program to extract the data). Then merge the data you want. You should be able to figure out the time zone for a city X by looking up its current time in File3 and finding a city Y with the same time (also from File 3), that is also in File 1 (which lists the time zone of city Y, and will hence be the TZ of X too). Just an idea..... > Hi all, > I'm looking for a free world cities data base that includes: > Longitude, latitude and time zone. > Thanks, > Sharon. > You could construct this using information from various WebPages. > E.G. > File 1: get a list of the tz zones: > http://en.wikipedia.org/wiki/List_of_tz_zones_by_country > (or download the source of this (see > http://en.wikipedia.org/wiki/Tz_database). Wikipedia cannot be relied upon under any circumstances... SignatureMark Rae ASP.NET MVP http://www.markrae.net >> You could construct this using information from various WebPages. >> E.G. [quoted text clipped - 4 lines] > > Wikipedia cannot be relied upon under any circumstances... Wikipedis ia very reliable as a starting point. As much as I dislike quoting politicians Ronald Reagan said "trust but verify." <%= Clinton Gallagher NET csgallagher AT metromilwaukee.com URL http://clintongallagher.metromilwaukee.com/ Thanks for your reply Fred. I cannot use this data. I should have mentioned that the format I need is: Longitude / Latitude: Long (42.5333333, 1.5333333) Time Zone: Integer (+1, -4) I found a good free cities database with longitude and latitude here: http://www.maxmind.com/download/worldcities/ Now all I need is the time zone. Regards, Sharon. > You could construct this using information from various WebPages. > E.G. [quoted text clipped - 26 lines] >> Thanks, >> Sharon. I have found a method to find the timezone using longitude of a place from somewhere. I tried it to do some calculations and found it working, it is not very accurate though (needs some improvements) The timezone changes every 15 degrees on longitude either way. The formula to find timezone is: (longitude/15) * 3600; This will give you timezone (or time differnce from GMT) in seconds. And can be used in calculations. Hope this will help. Regards, A Kamran EggHeadCafe - .NET Developer Portal of Choice http://www.eggheadcafe.com What you are calculating is local mean time, not zone time. Time zones are established by law, usually follow 1-hour increments, and have boundaries that are not straight lines. For example, Atlanta (longitude 84 west) is 5.6 hours behind GMT according to your formula, but in fact it is officially 5 hours in the winter and 4 hours in the summer. Local mean time is almost always within 1 hour of official (standard) zone time. >I have found a method to find the timezone using longitude of a place from >somewhere. I tried it to do some calculations and found it working, it is [quoted text clipped - 16 lines] > EggHeadCafe - .NET Developer Portal of Choice > http://www.eggheadcafe.com Yes daylight saving time is also a problem. I finally decided to buy the Meridian Global Cities Database. http://www.meridianworlddata.com/Matrix.asp?guid=A0C3B319-A8A7-4987-8139-6347414 69652&Product%5fint%5fid=158&Region%5fint%5fid=113&Edition%5fint%5fid=102&Licens e%5fstr%5ftype=Commercial It includes DST rules. Thanks for your help, Sharon. > What you are calculating is local mean time, not zone time. Time zones > are established by law, usually follow 1-hour increments, and have [quoted text clipped - 27 lines] >> EggHeadCafe - .NET Developer Portal of Choice >> http://www.eggheadcafe.com Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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