/in/foo.cc: In function 'int main()':
/in/foo.cc:42:4: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   c+=num[3]*i;
   ~^~~~~~~~~~
/in/foo.cc:33:4: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
   b+=num[2]*i;
   ~^~~~~~~~~~
/in/foo.cc:24:4: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   a+=num[1]*i;
   ~^~~~~~~~~~