Answer to Quiz 9 Fri 23 Mar 2001

        typedef struct person PERSON;
        struct person
        {
           char   *name;
           int    age;
           PERSON *tail;
        };

1. The function int CountMinors ( PERSON *l ); returns the number of persons in l of age strictly less than 18. Write a recursive definition of this function below.

           int CountMinors ( PERSON *l )
           {
              if (l == NULL)
                 return 0;
              else if (l -> age < 18)
                 return 1 + CountMinors(l -> tail);
              else
                 return CountMinors(l -> tail);
           }
   

2. The function void Destroy ( PERSON *l ); frees all memory allocated for l.
   Write an implementation for Destroy below.

           void Destroy ( PERSON *l )
           {
              if (l != NULL)
              {
                 Destroy(l -> tail);
                 free(l -> name);
                 free(l);
              }
           }