Compilare: user.cpp: In function 'int main()': user.cpp:28: warning: comparison between signed and unsigned integer expressions user.cpp:29: warning: comparison between signed and unsigned integer expressions user.cpp:30: warning: comparison between signed and unsigned integer expressions user.cpp:36: warning: comparison between signed and unsigned integer expressions user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp:20: warning: 'x2' may be used uninitialized in this function user.cpp:20: warning: 'x1' may be used uninitialized in this function