I've already a got a lesson trying to be a an Almighty, but still I've some juice to continue the discussion. Here is what I understand 1. const char *p = "abcde"; // p points to a string whose content cannot be modified */ char p[] = "pqrst"; p = q; // the pointer can be modified, not the content p[0] = 0; // error 2. char *const p = "abcde"; char q[] = "pqrst"; p = q; /* compile error: p is a constant */ but p[0] = 0; /* no compile error, but compiler dependant, may cause a fault */ 3. const char *const p = "abcde"; char q[] = "pqrst"; p = q; /* compile error: p is a constant */ p[0] = 0; /* compile error */