GPKG not recognized as a supported file format - c++

Question

I try to read in a gpkg file to extract geo informations like streets and buildings.
Therefor I started with this code:
#include "gdal_priv.h"
#include <iostream>
int main() {
GDALDataset* poDataset;
GDALAllRegister();
std::cout << "driver# " << GetGDALDriverManager()->GetDriverCount()
<< std::endl;
for (int i = 0; i < GetGDALDriverManager()->GetDriverCount(); i++) {
auto driver = GetGDALDriverManager()->GetDriver(i);
auto info = driver->GetDescription();
std::cout << "driver " << i << ": " << info << std::endl;
}
auto driver = GetGDALDriverManager()->GetDriverByName("GPKG");
poDataset = (GDALDataset*)GDALOpen("Building_LoD1.gpkg", GA_ReadOnly);
if (poDataset == NULL) {
// ...;
}
return 0;
}
The driver list contains GPKG, but the reading fails with an error that the file is not recognized as supported file format.
Doing a gdalinfo Building_LoD1.gpkg leads to the same error in the console. But I can open the file in QGIS.
And a gdalsrsinfo Building_LoD1.gpk reports:
PROJ.4 : +proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +k_0=1 +x_0=2600000 +y_0=1200000 +ellps=bessel +towgs84=674.374,15.056,405.346,0,0,0,0 +units=m +no_defs
OGC WKT :
PROJCS["CH1903+ / LV95",
GEOGCS["CH1903+",
DATUM["CH1903+",
SPHEROID["Bessel 1841",6377397.155,299.1528128,
AUTHORITY["EPSG","7004"]],
TOWGS84[674.374,15.056,405.346,0,0,0,0],
AUTHORITY["EPSG","6150"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4150"]],
PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],
PARAMETER["latitude_of_center",46.95240555555556],
PARAMETER["longitude_of_center",7.439583333333333],
PARAMETER["azimuth",90],
PARAMETER["rectified_grid_angle",90],
PARAMETER["scale_factor",1],
PARAMETER["false_easting",2600000],
PARAMETER["false_northing",1200000],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","2056"]]
Does anyone know why a gpkg file might be reported as not supported?
The gdal version is 2.3.2.

Answer 1

I figured out the problem. The reason for the message is not that the file format is not support by gdal, but that I used the wrong function to open the file.
If I want to read in a file that has vector information then I need to use:
GDALDataset* poDS;
poDS = (GDALDataset*)GDALOpenEx( "Building_LoD1.gpkg", GDAL_OF_VECTOR, NULL, NULL, NULL);