Compilare: user.cpp: In function ‘int main()’: user.cpp:134:9: warning: unused variable ‘a’ [-Wunused-variable] int a, b; ^ user.cpp:134:12: warning: unused variable ‘b’ [-Wunused-variable] int a, b; ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:42:41: 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 ‘InputReader::InputReader(const char*)’: user.cpp:20:39: 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); ^