Compilare: user.cpp: In function ‘void read_data()’: user.cpp:11: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:15: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:44: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result