Compilare: user.cpp: In function ‘void add_w(char*)’: user.cpp:27:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < strlen(w)) ^ user.cpp: In function ‘void delete_w(char*, int, trie*&)’: user.cpp:46:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1 < strlen(w)) delete_w(w,i+1,next_it); ^ user.cpp:47:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == strlen(w)-1) it->t[poz]->end_of_w = false; ^ user.cpp: In function ‘int query_word(char*, int, trie*)’: user.cpp:58:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == strlen(w)-1) ^ user.cpp:69:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1 < strlen(w)) query_word(w,i+1,it->t[poz]); ^ user.cpp: In function ‘int query_prefix(char*, int, trie*, int)’: user.cpp:80:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1 < strlen(w)) query_prefix(w,i+1,it->t[poz],total); ^ user.cpp: In function ‘int query_word(char*, int, trie*)’: user.cpp:72:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int query_prefix(char*, int, trie*, int)’: user.cpp:84:1: warning: control reaches end of non-void function [-Wreturn-type] } ^