Compilare: user.cpp: In function ‘int main()’: user.cpp:30:17: warning: variable ‘a’ set but not used [-Wunused-but-set-variable] int a,b,c,d; ^ user.cpp:30:19: warning: variable ‘b’ set but not used [-Wunused-but-set-variable] int a,b,c,d; ^ user.cpp:30:23: warning: variable ‘d’ set but not used [-Wunused-but-set-variable] int a,b,c,d; ^