Compilare: user.cpp: In function ‘void read()’: user.cpp:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void write()’: user.cpp:123: warning: format ‘%d’ expects type ‘int’, but argument 3 has type ‘long long int’