Compilare: main.cpp: In function 'void add_word(Node*, const string&, int)': main.cpp:59:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(poz==S.size()) ~~~^~~~~~~~~~ main.cpp: In function 'bool delete_word(Node*, const string&, int)': main.cpp:76:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(poz==S.size()) rad->dec_occ(); ~~~^~~~~~~~~~ main.cpp: In function 'int occurences(Node*, const string&, int)': main.cpp:93:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(poz==S.size()) ~~~^~~~~~~~~~ main.cpp: In function 'int longest_prefix(Node*, const string&, int)': main.cpp:103:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(poz==S.size() || rad->get_ptr_letter(S[poz])==NULL) ~~~^~~~~~~~~~