/in/foo.cc: In function 'int main()':
/in/foo.cc:23:12: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   now->coef=a;
   ~~~~~~~~~^~
/in/foo.cc:24:12: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   now->expo=b;
   ~~~~~~~~~^~