nrbun2.cpp: In function 'int main()': nrbun2.cpp:6: error: declaration does not declare anything nrbun2.cpp:4: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result nrbun2.cpp:5: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result