Description
You are asked to write a simple program that, as you will see, may not be as simple to write in C as it looks if you want to write robust programs. It will allow you to learn about basic input/output.
This program must prompt the user for the name of a first city, then its latitude and longitude, then for the name of a second city with its latitude and longitude, then compute the flying distance between the two and display. For example,
The first city: <>
The second city: <>
The distance between <first city> and <second city> is <result> km
Here is the formula for computing the distance (adapted from mathforum.org, provided by
Doctor Rob):
Assume the Earth is a perfect sphere. Let all angles be measured in signed degrees (negative latitude means South, negative longitude means West).
phi = 90 – latitude
The North Pole has phi = 0, the South Pole has phi = 180, and 0 <= phi <= 180.
theta = longitude
Greenwich, England, has theta = 0, and -180 <= theta <= 180.
Let the angles for the two points be (phi1, theta1) and (phi2, theta2). Then compute
c = sin(phi1)*sin(phi2)*cos(theta1-theta2) + cos(phi1)*cos(phi2)
Then the shortest great circle distance between the two points is
d = R*Arccos(c)*Pi/180
where R is the radius of the earth in kilometers, and the arccosine is taken between 0 and 180
degrees, inclusive. Earth radius: 6,371 km
ph
Some cities for testing:
-
city
latitude
longitude
Shenzhen
22.55
114.1
-
39.9139
116.3917
New York, USA
40.7127
-74.0059
San Francisco, USA
37.7833
-122.4167
London, UK
51.5072
-0.1275
Paris, France
48.8567
2.3508
Kolkata, India
22.567
88.367
Moscow, Russia
55.7500
37.6167
Rio de Janeiro, Brazil
-22.9083
-43.1964
Sydney, Australia
-33.865
151.209444
For checking out if your results are roughly correct:
http://www.worldatlas.com/travelaids/flight_distance.htm
