Compilare: user.cpp: In function 'void adauga(std::string)': user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void sterge(std::string)': user.cpp:58: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int nr_cuvinte(std::string)': user.cpp:72: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int prefix(std::string)': user.cpp:81: warning: comparison between signed and unsigned integer expressions