Beware NDEBUG controls assert

According to assert document, if NDEBUG is defined, assert actually does nothing:

#ifdef NDEBUG
#define assert(condition) ((void)0)
#else
#define assert(condition) /*implementation defined*/
#endif

So if your program doesn’t trigger assert as you expected, please check whether NDEBUG is defined or not. E.g., if you use cmake to manage the build process, set CMAKE_BUILD_TYPE‘s value as Release will define NDEBUG:

# cmake -DCMAKE_BUILD_TYPE=Release ..
# make VERBOSE=1
......
/opt/cuda/bin/nvcc ...... \"-Wall\",\"-fPIC\",\"-O3\",\"-DNDEBUG\" ...... 

assert(in >> n);