foo.cc: In function 'int main()':
foo.cc:8:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |         freopen("b.in","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:9:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 |         freopen("b.out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~

Found 10 testcases.