Distance calculation between two latitude and longitude degrees

Here is the code to calculate the distance between the two latitude and longitude, divided into: header file, source code and test code three parts.
Specific as follows:

1 //LatLonDistanceDlg.h: Header file2 //  3   4 #pragmaOnce5   6typedefstruct  7 {  8     DoubleDlongitude; 9     DoubleDlatitude; Ten}mylatlong_t,*pmylatlong_t;  One    A //Clatlondistancedlg dialog Box - classClatlondistancedlg: PublicCDialog - {   the     ......   -    -     voidDistanceoftwopositions (mylatlong_t Ll_posstart, mylatlong_t ll_posend,Double&dis);  - //Implement + protected:   -     ......   + };  A    at //LatLonDistanceDlg.cpp: Implementing Files - //   -    - //constant Definition - Const DoubleGCONSTPI =3.1415926536;  - //WGS-84 Long shaft radius in #defineEARTH_LONG_RADIUS_WGS84 6378137.0//Unit: M - //WGS-84 Earth Flat rate (terrestrial flattening) to #defineEARTH_FLATTENING_WGS84 298.257223563 + //meters per sea mile - #defineMeters_per_sea_mile 1852.0 the    * //input parameters: mylatlong_t is a structure, including longitude and latitude $ //output parameter: Ddistance is the return circle distancePanax Notoginseng voidClatlondistancedlg::D istanceoftwopositions (mylatlong_t startlatlong, mylatlong_t Endlatlong,Double&ddistance) - {   the     DoubleDinradians;  +     DoubleDtmpval =0.0;  A     DoubleDFi =0.0;  the     DoubleDFi2 =0.0;  +     DoubleDdrda = Endlatlong.dlongitude-Startlatlong.dlongitude;  -     DoubledTMP =0.0;  $     DoubleDTMP2 =0.0;  $    -Ddrda = Ddrda * GCONSTPI/180.0;//In radians -DFi =Startlatlong.dlatitude;  theDFi2 =Endlatlong.dlatitude;  -   WuyiDFi = DFi * GCONSTPI/180.0;//In radians theDFi2 = DFi2 * GCONSTPI/180.0;//In radians -    WuDtmpval = sin (dFi) * sin (dFi2) + cos (dFi) * cos (DFI2) *cos (DDRDA);  -     if(Fabs (Dtmpval) >1.0)   About     {   $AfxMessageBox (L"Invalidate value of arccos!");//Use Unicode Character Set -         return ;  -     }   -Dinradians = ACOs (dtmpval);//In radians AdTMP = (sin (dFi) +sin (dFi2));  +DTMP2 = (sin (dFi)-sin (dFi2));  theDtmpval = ((3* SIN (Dinradians)-Dinradians) * dtmp * dtmp)/(1+cos (dinradians));  -Dtmpval = Dtmpval-((3* SIN (Dinradians) + dinradians) * DTMP2 * dTmp2)/(1-cos (dinradians));  $    theddistance = earth_long_radius_wgs84 * Dinradians + (EARTH_LONG_RADIUS_WGS84/(4* earth_flattening_wgs84)) * DTMPVAL;//In meters the }   the    the //Test Code - //TODO: Add additional initialization code here in {   the     //Shenzhen Lily Hotel Latitude: 22.601369, longitude 114.115145 the     //Shenzhen Lily Star City Latitude: 22.601334, longitude 114.115807 About     //shenzhen Bouginon Batch latitude: 22.583596, longitude 114.112227 the mylatlong_t LatLon;  the mylatlong_t LatLon2;  the mylatlong_t LatLon3;  +     DoubleDDIs =0.0;  -    theLatlon.dlatitude =22.601369; BayiLatlon.dlongitude =114.115145;  theLatlon2.dlatitude =22.601334;  theLatlon2.dlongitude =114.115807;  -Latlon3.dlatitude =22.583596;  -Latlon3.dlongitude =114.112227;  the    the distanceoftwopositions (Latlon,latlon2,ddis);  theTRACE ("%f\r\n", DDIs);//68.177865 the distanceoftwopositions (Latlon,latlon3,ddis);  -TRACE ("%f\r\n", DDIs);//1990.891295 the}

Distance calculation between two latitude and longitude degrees