Compilare: main.cpp: In function 'int main()': main.cpp:21:6: warning: unused variable 'i' [-Wunused-variable] int i; ^ main.cpp: In function 'bool search(int)': main.cpp:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < h[val].size(); i++) if(h[val][i] == x) return 1; ~~^~~~~~~~~~~~~~~ main.cpp: In function 'void add(int)': main.cpp:44:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < h[val].size() && !ex; i++) if(h[val][i] == x) ex = true; ~~^~~~~~~~~~~~~~~