Compilare: user.cpp: In function ‘int main()’: user.cpp:32: warning: comparison between signed and unsigned integer expressions user.cpp:34: warning: comparison between signed and unsigned integer expressions user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp:44: warning: comparison between signed and unsigned integer expressions user.cpp:56: warning: comparison between signed and unsigned integer expressions user.cpp:59: warning: comparison between signed and unsigned integer expressions user.cpp:63: warning: comparison between signed and unsigned integer expressions user.cpp:66: warning: comparison between signed and unsigned integer expressions