Compilare: user.cpp:23: warning: this decimal constant is unsigned only in ISO C90 user.cpp:38: warning: this decimal constant is unsigned only in ISO C90 user.cpp: In function ‘int main()’: user.cpp:21: warning: comparison between signed and unsigned integer expressions user.cpp:25: warning: comparison between signed and unsigned integer expressions user.cpp:28: warning: comparison between signed and unsigned integer expressions user.cpp:34: warning: comparison between signed and unsigned integer expressions