[PROJ] Translate command into equivalent c++ function

[Thomas Knudsen]

Start by checking whether your call to proj_create_crs_to_crs succeeds
(i.e. whether it returns NULL or not, as also suggested in the PROJ
documentation over at https://proj.org/development/quickstart.html). And in
general always check the return status of function calls, cf. e.g.
https://proj.org/development/errorhandling.html

If NULL is returned, your PROJ installation is probably not complete
(lacking support files and/or setting of environment variables). In that
case follow the tracks laid out in https://proj.org/resource_files.html

/Thomas



Den ons. 29. mar. 2023 kl. 12.43 skrev Ali Akram <devtoona at gmail.com>:

> Hello,
>
> I want to use this to translate WSG84 to UMT and I am able to execute this
> command from terminal
> echo 56 12 | cs2cs +init=epsg:4326 +to +init=epsg:25832 with output as 6231950.54
> 1920310.71 0.00 now trying to achieve it from c++ code and here is my way
>
> PJ_CONTEXT *C;
> PJ *P;
> C = proj_context_create();
>
> P = proj_create_crs_to_crs(C, "EPSG:4326", "EPSG:6677", NULL);
> PJ_COORD input_coords, output_coords;
> input_coords = proj_coord(56,12, 0, 0);
> output_coords = proj_trans(P, PJ_FWD, input_coords);
> std::string result = "";
> result.append(std::to_string(output_coords.xy.x)+","+
> std::to_string(output_coords.xy.y));
> proj_destroy(P);
> proj_context_destroy(C);
>
>
> But it returns to me the same coordinates that I send in input i.e, 56,12 .
> Kindly help thanks
>
> Regards,
> Ali
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