Compilare: user.cpp: In function ‘int main()’: user.cpp:78:16: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] ans [++ u] = NULL; ^ user.cpp:49:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("paznici.in", "r", stdin); ^ user.cpp:50:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("paznici.out", "w", stdout); ^ user.cpp:52:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d\n", &n, &m); ^ user.cpp:54:17: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets (s); ^ /tmp/ccClnt7o.o: In function `main': user.cpp:(.text.startup+0x92): warning: the `gets' function is dangerous and should not be used.