Compilare: user.cpp: In function ‘int common_prefix(int, int)’: user.cpp:15:96: warning: NULL used in arithmetic [-Wpointer-arith] while(words[pointer][result]==words[dictionary[position]][result]&&words[pointer][result]!=NULL) ^ user.cpp: In function ‘int binary_string_search(int)’: user.cpp:26:38: warning: NULL used in arithmetic [-Wpointer-arith] if(words[pointer][position]==NULL&&words[dictionary[middle]][position]==NULL) ^ user.cpp:26:81: warning: NULL used in arithmetic [-Wpointer-arith] if(words[pointer][position]==NULL&&words[dictionary[middle]][position]==NULL) ^ user.cpp: In function ‘int get_maximum_prefix(int)’: user.cpp:55:62: warning: unused variable ‘auxiliar’ [-Wunused-variable] int position=binary_string_search(pointer),position_copy,auxiliar,maximum_prefix=0; ^ user.cpp: In function ‘int main()’: user.cpp:75:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.in","r",stdin); ^ user.cpp:76:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trie.out","w",stdout); ^ user.cpp: In function ‘int binary_string_search(int)’: user.cpp:20:56: warning: ‘maximum_position’ may be used uninitialized in this function [-Wmaybe-uninitialized] int left=1,right=dictionary_size+1,middle,position,maximum_position,maximum_common=0; ^ /tmp/ccS6MkrY.o: In function `main': user.cpp:(.text.startup+0xa2): warning: the `gets' function is dangerous and should not be used.