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#include <stdio.h>
#include <proj.h>
int main (void) {
PJ_CONTEXT *C;
PJ *P;
PJ* P_for_GIS;
PJ_COORD a, b;
/* or you may set C=PJ_DEFAULT_CTX if you are sure you will */
/* use PJ objects from only one thread */
C = proj_context_create();
P = proj_create_crs_to_crs (C,
"EPSG:4326",
"+proj=utm +zone=32 +datum=WGS84", /* or EPSG:32632 */
NULL);
if (0==P) {
fprintf(stderr, "Oops\n");
return 1;
}
/* This will ensure that the order of coordinates for the input CRS */
/* will be longitude, latitude, whereas EPSG:4326 mandates latitude, */
/* longitude */
P_for_GIS = proj_normalize_for_visualization(C, P);
if( 0 == P_for_GIS ) {
fprintf(stderr, "Oops\n");
return 1;
}
proj_destroy(P);
P = P_for_GIS;
/* a coordinate union representing Copenhagen: 55d N, 12d E */
/* Given that we have used proj_normalize_for_visualization(), the order of
/* coordinates is longitude, latitude, and values are expressed in degrees. */
a = proj_coord (12, 55, 0, 0);
/* transform to UTM zone 32, then back to geographical */
b = proj_trans (P, PJ_FWD, a);
printf ("easting: %.3f, northing: %.3f\n", b.enu.e, b.enu.n);
b = proj_trans (P, PJ_INV, b);
printf ("longitude: %g, latitude: %g\n", b.lp.lam, b.lp.phi);
/* Clean up */
proj_destroy (P);
proj_context_destroy (C); /* may be omitted in the single threaded case */
return 0;
}
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