Compilare: main.cpp: In function 'void make_prefix(std::__cxx11::string)': main.cpp:23:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < pattern.length(); ++i) ~~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'void search(std::__cxx11::string, std::__cxx11::string)': main.cpp:45:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < str.length(); ++i) ~~^~~~~~~~~~~~~~ main.cpp:57:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (state_j == pattern.length()) ~~~~~~~~^~~~~~~~~~~~~~~~~~~