Hi, There is interesting example about NULL and reference usage in C++ :) typedef struct { int a [2]; } s_t; int bar(int v, s_t &s) { return v ? s.a[0] : 0; } int main(int argc, char * argv []) { s_t local; s_t * ptr = &local; ptr = 0; ((void)(argv)); return bar(argc - 1, *ptr); } Which line do you expect that APP crashes ? Regards