Compilare: main.cpp: In function 'int main()': main.cpp:21:22: warning: comparison of integer expressions of different signedness: 'int' and 'const std::__cxx11::basic_string<char>::size_type' {aka 'const long unsigned int'} [-Wsign-compare] 21 | if (idx_open != std::string::npos) { | ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~ main.cpp:23:30: warning: comparison of integer expressions of different signedness: 'int' and 'const std::__cxx11::basic_string<char>::size_type' {aka 'const long unsigned int'} [-Wsign-compare] 23 | } else if (idx_close != std::string::npos) { | ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~