Compilare: user.cpp: In function ‘void read()’: user.cpp:43: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:45: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:109: warning: unused variable ‘i’ user.cpp:109: warning: unused variable ‘j’ user.cpp:109: warning: unused variable ‘k’ user.cpp:109: warning: unused variable ‘l’