There are some basic things that are wrong with the above code. That's why the output doesn't make sense. You can't equate p to def since p is a pointer to char while def is a pointer to pointer to char. In fact the proper declaration for p and the code should be...

Code:

char **p = def;
p=p+40;
printf("%s\n",*p);

The problem occurs probably because def is being cast to a unilevel pointer as in (char *)def and hence outputs garbage.