Compilare: user.cpp: In function ‘int main()’: user.cpp:133:9: warning: unused variable ‘x’ [-Wunused-variable] int x,y; ^ user.cpp:133:11: warning: unused variable ‘y’ [-Wunused-variable] int x,y; ^ user.cpp: In member function ‘void instream::advance()’: user.cpp:115:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer,SIZE,1,input_file); ^ user.cpp: In constructor ‘instream::instream(const char*)’: user.cpp:89:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer,SIZE,1,input_file); ^