foo.cc: In member function 'bool num::check(int)':
foo.cc:41:14: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
   if(val>>w&1!=0)return true;
             ~^~~
foo.cc: In member function 'bool num::change(int)':
foo.cc:46:2: warning: no return statement in function returning non-void [-Wreturn-type]
  }
  ^
foo.cc: In member function 'int num::get()':
foo.cc:51:2: warning: control reaches end of non-void function [-Wreturn-type]
  }
  ^

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