Compilare: user.cpp: In function ‘int main()’: user.cpp:38: warning: comparison between signed and unsigned integer expressions user.cpp:39: warning: comparison between signed and unsigned integer expressions user.cpp:63: warning: comparison between signed and unsigned integer expressions user.cpp:64: warning: comparison between signed and unsigned integer expressions user.cpp:69: warning: comparison between signed and unsigned integer expressions user.cpp:70: warning: comparison between signed and unsigned integer expressions user.cpp:71: warning: comparison between signed and unsigned integer expressions user.cpp:71: warning: comparison between signed and unsigned integer expressions user.cpp:72: warning: comparison between signed and unsigned integer expressions