# How to convert lat long to UTM

I want to convert two double (`double longitude_wgs84_radians, double altitude_wgs84_meters`) which I get from a function.

The coordinates looks like

``````latitude_wgs84_radians: 0.924593
``````

How can I convert them into UTM in C++? A code example or documentation would be nice.

I tried the example code from GeographicLib 1.49

``````// Example of using the GeographicLib::UTMUPS class
#include <iostream>
#include <iomanip>
#include <exception>
#include <string>
#include <GeographicLib/UTMUPS.hpp>
using namespace std;
using namespace GeographicLib;
int main() {
try {
{
// Sample forward calculation
double lat = 33.3, lon = 44.4; // Baghdad
int zone;
bool northp;
double x, y;
UTMUPS::Forward(lat, lon, zone, northp, x, y);
string zonestr = UTMUPS::EncodeZone(zone, northp);
cout << fixed << setprecision(2)
<< zonestr << " " << x << " " << y << "\n";
}
{
// Sample reverse calculation
string zonestr = "38n";
int zone;
bool northp;
UTMUPS::DecodeZone(zonestr, zone, northp);
double x = 444e3, y = 3688e3;
double lat, lon;
UTMUPS::Reverse(zone, northp, x, y, lat, lon);
cout << lat << " " << lon << "\n";
}
}
catch (const exception& e) {
cerr << "Caught exception: " << e.what() << "\n";
return 1;
}
}
``````

but if Im trying to compile it, I get 3. errors.

``````undefined reference to `GeographicLib::UTMUPS::EncodeZone(int, bool, bool)'
undefined reference to `GeographicLib::UTMUPS::Forward(double, double, int&, bool&, double&, double&, double&, double&, int, bool)'
collect2: error: ld returned 1 exit status
``````
• Perhaps this post might help: Convert Lat/Long to UTM specifying which zone to use (C++) Nov 13, 2017 at 14:31
• If you are using R, you need to use a function spTransform from the sp package: spTransform (x, "mention coordinate system in proj4s format") Nov 13, 2017 at 15:12
• @VijayRamesh Im sorry, what do you mean with R? Its my first experience with geographic systems. Nov 13, 2017 at 15:23
• Yes, geograpiclib geographiclib.sourceforge.io
– GBG
Nov 13, 2017 at 17:07
• @GBG just tried to use the example, but this is not working. Nov 13, 2017 at 17:22