Summary prototype and if structures - c++

Question

So I need to create a function that will turn the COUT part ONLY of each "if" statement:
// Respond to the user's menu selection
if (choice == ADULT_CHOICE)
{
charges = months * ADULT;
cout << over3 << "The total charges are $" << charges << endl;
}
else if (choice == CHILD_CHOICE)
{
charges = months * CHILD;
cout << over3 << "The total charges are $" << charges << endl;
}
else if (choice == SENIOR_CHOICE)
{
charges = months * SENIOR;
cout << over3 << "The total charges are $" << charges << endl;
}
Into a summary function that reads like THIS.
So far I have made a total mess of the code and I really need some help... here is what I have so far but most of it is probably not salvageable:
function prototype:
int summary(string, int, int, double);
Main:
//variables
int choice; // menu choice
int months; //number of months
double charges; //monthly charges
string type1 = "Adult", type2 = "Child", type3 = "Senior";
if (choice == ADULT_CHOICE)
{
charges = months * ADULT;
cout << summary(type1, months, 40, charges);
}
else if (choice == CHILD_CHOICE)
{
charges = months * CHILD;
cout << summary(type2, months, 20, charges);
}
else if (choice == SENIOR_CHOICE)
{
charges = months * SENIOR;
cout << summary(type3, months, 30, charges);
}
function definition:
int summary(string type, int months, int price , double charges)
{
system("CLS");
cout << down7;
cout << over3 << " Summary of Charges \n"
<< over3 << "----------------------------\n"
<< over3 << "Membership Type: " << type << endl;
cout << over3 << "Number of Months: " << months << endl;
cout << over3 << "Membership Prices: " << price << endl;
cout << over3 << "Total of Charges: " << charges << endl;
}
I know there is a lot wrong here and I just needed some help going in the right direction. I have no idea how to solve the string variable stuff, should I keep going that route? or go an other way entirely?
Thanks for any help!

Answer 1

There are several designs and implementations for your requirements.
switch statement
Instead of all these if-else-if in a ladder, use a switch statement. I believe a switch statement would be more readable:
double rate = 0.0;
std::string type_name;
double price = 0.0;
switch (choice)
{
case ADULT_CHOICE:
rate = adult_rate;
type_name = "Adult";
price = 40;
break;
case CHILD_CHOICE:
rate = child_rate;
type_name = "Child";
price = 20;
break;
case SENIOR_CHOICE:
rate = senior_rate;
type_name = "Senior";
price = 30;
break;
default:
cerr << "Invalid ticket type\r\n";
exit(1);
}
charges = months * rate;
summary(type_name, months, price, charges);
Look up table
A more maintainable design and implementation is to use a look up table. Create a table of entries that contain information about a ticket. (This will lead up to the last design consideration).
struct Ticket
{
unsigned int choice;
char const * type_name;
double price;
double rate;
};
const Ticket ticket_info[] =
{
{ADULT_CHOICE, "Adult", 40, ADULT_RATE},
{CHILD_CHOICE, "Child", 10, CHILD_RATE},
{SENIOR_CHOICE, "Senior", 30, SENIOR_RATE},
};
const unsigned int maximum_ticket_types =
sizeof(ticket_info) / sizeof(ticket_info[0]);
for (unsigned int i = 0; i < maximum_ticket_types; ++i)
{
if (choice == ticket_info[i].choice)
{
summary(ticket_info[i].type_name,
months,
ticket_info[i].price,
ticket_info[i].rate * months);
break;
}
}
This has the advantage that you can test it with only 1 entry and then add additional entries without adding additional code.
Object Oriented
In the Object Oriented approach, you would have either a ticket object (like the structure above) or have Parent Ticket and child ticket objects. The objects would contain methods for printing a summary.
Here is a sample:
class Ticket_Base
{
public:
friend std::ostream& operator>>(std::ostream& output, const Ticket_Base& ticket);
double rate;
double price;
std::string type_name;
};
class Adult_Ticket : public Ticket_Base
{
public:
Adult_Ticket()
: rate(ADULT_RATE), price(40), type_name("Adult");
};
The senior and child ticket classes would look the same as the adult ticket.
You could use the Factory Pattern to create tickets and a generic function to print the ticket summary.