Compilare: user.cpp: In function ‘int doit()’: user.cpp:35:12: warning: unused variable ‘i’ [-Wunused-variable] int n, i, j, k; ^ user.cpp:35:15: warning: unused variable ‘j’ [-Wunused-variable] int n, i, j, k; ^ user.cpp:35:18: warning: unused variable ‘k’ [-Wunused-variable] int n, i, j, k; ^ /tmp/ccvANjyv.o: In function `main': user.cpp:(.text.startup+0x6b): warning: the `gets' function is dangerous and should not be used.