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What kind of representation should we use for Appts? Since even a busy executive probably has fewer than a dozen appointments in a single day, a linear structure would be quite appropriate, so we will use a Block of Appointments:
#include <Block.h>
class Appts {
Block<Appointment> appts;
int nappts;
public:
Appts() : nappts(0) {}
void add(const Appointment& a) {
appts.reserve(nappts);
appts[nappts++] = a;
}
};
Notice that we also maintain the number of appointments;
this is because Blocks (like arrays)
do not keep track of the number of cells occupied
by meaningful data.
Keeping the Appointments for a given Date sorted would simplify matters, because that's the way we have been asked to display them. To do this, we can use an algorithm from Array_alg(C++). The algorithm insert() requires that its element type have a total order relation defined by operator< (its manpage tells us this), so we must add one to Appointment:
int operator<(const Appointment& a,
const Appointment& b) {
return a.time < b.time;
}
Now we can use insert() to add
an Appointment to the Block:
#include <Array_alg.h>
class Appts {
public:
void add(const Appointment& a) {
appts.reserve(nappts);
insert(&a[0], &appts[0], &appts[nappts]);
++nappts;
}
// ...
};
Finally, we will also have need of the following
functions:
class Appts {
int num() const {
return nappts;
}
const Appointment& operator[](int i) const {
return appts[i];
}
// ...
};
The first returns the number of Appointments in
the collection, and the section returns a reference to the i'th
one.
As with the extra functions in Calendar, these functions were added only when
their utility became obvious.