/in/foo.c: In function 'main':
/in/foo.c:8:11: warning: format '%a' expects argument of type 'double', but argument 2 has type 'int' [-Wformat=]
  printf("%a,%b",a+b);
           ^
/in/foo.c:8:14: warning: unknown conversion type character 'b' in format [-Wformat=]
  printf("%a,%b",a+b);
              ^