Compilare: user.cpp:4: warning: ISO C++ forbids declaration of ‘main’ with no type user.cpp: In function ‘int main()’: user.cpp:16: warning: suggest parentheses around ‘&&’ within ‘||’ user.cpp:22: warning: format ‘%d’ expects type ‘int’, but argument 3 has type ‘long int’ user.cpp:12: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result