/in/foo.cc: In function 'int main()':
/in/foo.cc:5:10: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  int a,b,c;
          ^
/in/foo.cc:6:3: warning: 'a' is used uninitialized in this function [-Wuninitialized]
  c=a+b;
  ~^~~~
/in/foo.cc:6:3: warning: 'b' is used uninitialized in this function [-Wuninitialized]