Compilare: user.cpp: In function ‘void parse(std::string, std::ofstream&)’: user.cpp:19:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] }while(i != string::npos); ^ user.cpp:24:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while( i != string::npos) { ^ user.cpp: In function ‘int main()’: user.cpp:51:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ( !sir.empty() && a == string::npos ){ ^