/in/foo.cc: In function 'int main()':
/in/foo.cc:29:15: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[8]' [-Wformat=]
  scanf("%s",&a);scanf("%s",&b);
               ^
/in/foo.cc:29:30: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[8]' [-Wformat=]
  scanf("%s",&a);scanf("%s",&b);
                              ^
/in/foo.cc:32:11: warning: 'num' is used uninitialized in this function [-Wuninitialized]
   if(a[num]==0)
      ~~~~~^