Compilare: user.cpp: In function ‘void read_data()’: user.cpp:9: warning: unused variable ‘j’ user.cpp:8: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:10: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result user.cpp:12: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result user.cpp:10: warning: ‘i’ is used uninitialized in this function