Compilare: user.cpp: In function ‘long long int read_nr()’: user.cpp:21:30: warning: NULL used in arithmetic [-Wpointer-arith] for( j=0 , nr=0; sir[j]!=NULL ; j++){ ^ user.cpp: In function ‘int main()’: user.cpp:38:36: warning: NULL used in arithmetic [-Wpointer-arith] for( j=0 , nr=0; sir[j] != NULL ; j++){ ^ user.cpp: In function ‘long long int read_nr()’: user.cpp:19:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sir); ^ user.cpp: In function ‘int main()’: user.cpp:31:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dtcsu.in","r",stdin); ^ user.cpp:32:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dtcsu.out","w",stdout); ^ user.cpp:36:18: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(sir); ^ /tmp/ccHI5Tj3.o: In function `read_nr()': user.cpp:(.text+0x17): warning: the `gets' function is dangerous and should not be used.