Compilare: user.cpp: In function 'int extra(std::string, std::string)': user.cpp:9: warning: comparison between signed and unsigned integer expressions user.cpp:9: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int main()': user.cpp:20: warning: format '%s' expects type 'char*', but argument 2 has type 'char (*)[128]' user.cpp:26: warning: comparison between signed and unsigned integer expressions