Compilare: user.cpp: In function 'int main()': user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp:33: warning: comparison between signed and unsigned integer expressions user.cpp:36: warning: comparison between signed and unsigned integer expressions user.cpp:40: warning: comparison between signed and unsigned integer expressions user.cpp:46: warning: comparison between signed and unsigned integer expressions user.cpp:51: warning: comparison between signed and unsigned integer expressions user.cpp:54: warning: comparison between signed and unsigned integer expressions user.cpp:58: warning: comparison between signed and unsigned integer expressions user.cpp:64: warning: comparison between signed and unsigned integer expressions user.cpp:74: warning: comparison between signed and unsigned integer expressions user.cpp:77: warning: comparison between signed and unsigned integer expressions user.cpp:81: warning: comparison between signed and unsigned integer expressions