Compilare: user.cpp:4: warning: ISO C++ forbids declaration of ‘main’ with no type user.cpp: In function ‘int main()’: user.cpp:15: warning: suggest parentheses around ‘&&’ within ‘||’ user.cpp:31: warning: format ‘%d’ expects type ‘int’, but argument 3 has type ‘long int’ user.cpp:9: warning: unused variable ‘i’