Compilare: main.cpp: In function 'bool NFA(std::string&)': main.cpp:25:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 25 | if (index < str.length()) { | ~~~~~~^~~~~~~~~~~~~~ main.cpp:33:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | else if (index == str.length()) { | ~~~~~~^~~~~~~~~~~~~~~