Compilare: user.cpp: In function ‘int main()’: user.cpp:25:9: warning: unused variable ‘i’ [-Wunused-variable] int i, j; ^ user.cpp:25:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j; ^ user.cpp: In function ‘void Prefixe()’: user.cpp:41:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j, k, l; ^ user.cpp:41:15: warning: unused variable ‘k’ [-Wunused-variable] int i, j, k, l; ^