如何从Main调用void函数

Question

In my program I am trying to call the void function from Main but I can't figure out the correct way.

Main is at the very bottom and void GetTicketType(char &Choice) is the function I need to call to cout the ticket type.

//---------------------------------------------------------------------------
// Purpose: This program simulates a ticket office for sporting events
// Author: TBA
// Date: TBA
//---------------------------------------------------------------------------
#include <iostream>
#include <iomanip>
using namespace std;

const char CASH = 'C';
const char CREDIT = 'D';
const char NOSEBLEED = 'N';
const char BOX_SEAT = 'B';
const char FIFTY_YARD_LINE = 'F';
const char STUDENT_SECTION = 'S';
const float NOSEBLEED_PRICE = 43.42;
const float BOX_SEAT_PRICE = 353.85;
const float FIFTY_YARD_LINE_PRICE = 94.05;
const float STUDENT_SECTION_PRICE = 19.99;

//---------------------------------------------------------------
// Function: ConfirmChoice
// Purpose: Confirms the users ticket purchase before processing payment
// Parameters: TicketType - The type of ticket selected
// Returns: true if the user confirms the selection, false otherwise
//--------------------------------------------------------------
bool ConfirmChoice(const char TicketType)
{
char Choice;
bool Confirmed;

// Print out their selection
cout << "\nYou have chosen to purchase ";
cout << fixed << setprecision(2);
switch (TicketType)
{
case NOSEBLEED:
cout << "Nosebleed ticket(s) at a price of $";
cout << NOSEBLEED_PRICE << ".\n";
break;
case BOX_SEAT:
cout << "Box Seat ticket(s) at a price of $";
cout << BOX_SEAT_PRICE << ".\n";
break;
case FIFTY_YARD_LINE:
cout << "Ticket(s) on the 50 yard line at a price of $";
cout << FIFTY_YARD_LINE_PRICE << ".\n";
break;
case STUDENT_SECTION:
cout << "Ticket(s) in the Student Section at a price of $";
cout << STUDENT_SECTION_PRICE << ".\n";
break;
}

// Confirm the selection
cout << "Do you wish to confirm your purchase? Enter Y or N: ";
cin >> Choice;
Choice = toupper(Choice);
while (Choice != 'Y' && Choice != 'N')
{
cout << "Invalid selection. Please enter either Y or N: ";
cin >> Choice;
Choice = toupper(Choice);
}
Confirmed = (Choice == 'Y');

// Check confirmation 
if (Confirmed)
cout << "You have confirmed your choice.\n" << endl;
else
cout << "You not confirmed your choice.\n" << endl;
return (Confirmed);
}

//-------------------------------------------
// Function: CalculateChange
// Purpose: To output the change due
// Parameters: ChangeDue - The amount of change needed 
// Returns: Nothing
//-------------------------------------------
void CalculateChange(const float ChangeDue)
{
int Change = 0;
int Dollars = 0;
int Quarters = 0;
int Dimes = 0;
int Nickels = 0;
int Pennies = 0;

// Compute change 
Change = ChangeDue * 100;
Dollars = Change / 100;
Change = Change % 100;
Quarters = Change / 25;
Change = Change % 25;
Dimes = Change / 10;
Change = Change % 10;
Nickels = Change / 5;
Pennies = Change % 5;

// Print out change
cout << "Your change is \n\t";
cout << Dollars << " Dollars\n\t";
cout << Quarters << " Quarters\n\t";
cout << Dimes << " Dimes\n\t";
cout << Nickels << " Nickels\n\t";
cout << Pennies << " Pennies\n";
}

//---------------------------------------------------------------------------
// Function: CalculateCost
// Purpose: Calculate the cost of the ticket purchase(s) (num_tickets * price_per_ticket)
// Parameters: PricePerTicket - Ticket price based on the type of ticket
// Returns: The cost of purchasing the chosen number of tickets 
//---------------------------------------------------------------------------
float CalculateCost(const float PricePerTicket)
{
int TicketCount;
float Cost;

cout << "How many tickets would you like? Please enter a positive integer value: ";
cin >> TicketCount;
while (TicketCount < 0)
{
cout << "Invalid entry. Please re-enter: ";
cin >> TicketCount;
}

Cost = PricePerTicket * TicketCount;
cout << "Your bill is: $" << fixed << setprecision(2) << Cost << endl;
return Cost;
}

//---------------------------------------------------------------------------
// Function: GetPaymentType
// Purpose: Ask the user how they want to pay, cash or credit
// Parameters: None
// Returns: Value is CREDIT or CASH (global character constants) 
//---------------------------------------------------------------------------
char GetPaymentType()
{
char Choice;

// Print the main menu describing the ticket payment types 
cout << "+-------------------------------------------------------+\n";
cout << "+ Welcome to our Ticket Office +\n";
cout << "+-------------------------------------------------------+\n";
cout << endl << endl;

// Cash or credit card (in upper case)
cout << "How would you like to pay?\n";
cout << "Enter C for cash or D for credit card: ";
cin >> Choice;
Choice = toupper(Choice);
while (Choice != CASH && Choice != CREDIT)
{
cout << "Invalid choice. Please enter C for cash or D for credit card: ";
cin >> Choice;
Choice = toupper(Choice);
}
return Choice;
}

//---------------------------------------------------------------------------
// Function: GetTicketType
// Purpose: Get the customer's choice between 4 types of tickets
// Parameters: Choice - Set to the user's choice
// Returns: Nothing
//---------------------------------------------------------------------------
void GetTicketType(char &Choice)
{
// Ask the customer what type of ticket s/he prefers to buy 
cout << "\nWhat type of ticket would you like?\n";
cout << "\t" << NOSEBLEED << " for Nosebleed Section, Price = $";
cout << NOSEBLEED_PRICE << endl;
cout << "\t" << BOX_SEAT << " for Box Seats, Price = $";
cout << BOX_SEAT_PRICE << endl;
cout << "\t" << FIFTY_YARD_LINE << " for Seats on the Fifty Yard Line, Price = $";
cout << FIFTY_YARD_LINE_PRICE << endl;
cout << "\t" << STUDENT_SECTION << " for Student Section, Price = $";
cout << STUDENT_SECTION_PRICE << endl;

// Get ticket choice (in upper case)
cout << "Enter choice: ";
cin >> Choice;
Choice = toupper(Choice);   
while (Choice != NOSEBLEED && Choice != BOX_SEAT && 
Choice != FIFTY_YARD_LINE && Choice != STUDENT_SECTION)
{
cout << "Invalid choice. Please re-enter: ";
cin >> Choice;
Choice = toupper(Choice);
}
}

//---------------------------------------------------------------------------
// Function: PayWithCash
// Purpose: Handles payment by cash. Asks the user for the money until
// they enter enough, then updates the ChangeDue parameter
// Parameters: Cost - The amount due for the purchase
// ChangeDue - The amount of change due to customer
// Returns: Nothing
//---------------------------------------------------------------------------
void PayWithCash(const float Cost, float &ChangeDue)
{
float CashOffered;

// Pay in cash
cout << "Please enter enough cash. Your bill is $" << Cost << ": $ ";
cin >> CashOffered;

// Check sufficiency
while (CashOffered < Cost)
{
cout << "That is not enough to pay for your purchase!\n"
<< " Please enter at least $" << Cost << ": ";
cin >> CashOffered;
}

// Calculate change
ChangeDue = CashOffered - Cost;
}

//---------------------------------------------------------------------------
// Function: PayWithCredit
// Purpose: Handles payment by credit. Basically, just prints a statement
// telling them that their card will be charged.
// Parameters: const float Cost - the amount due for the purchase
// Returns: Nothing
//---------------------------------------------------------------------------
void PayWithCredit(const float Cost)
{
cout << "Your credit card will be billed for $" << Cost << ".\n";
}

//---------------------------------------------------------------------------
// Function: main
// Purpose: This is the main program that calls functions above.
// Parameters: None
// Returns: Nothing
//---------------------------------------------------------------------------
int main()
{
// Declarations 

char TChoice ;   // Ticket type: Nosebleed, box seats etc.. 
TChoice << GetTicketType( &TChoice);
char PChoice = GetPaymentType() ;    // Payment choice: cash or credit card
bool Confirmed;  // Did the user confirm the selection
float Cost;  // The cost of the ticket puchased
float ChangeDue;     // The amount of change owed (for cash purchases)

// Print your name and UAID

// Get the choice of payment type

// Get the choice of ticket type
GetTicketType(TChoice );
{
cout << "You have chosen the " << TChoice << "tickets. " <<".\n";
}

// Confirm the selection

// If they confirm the purchase

// Call functions to figure out the price of ticket purchase(s) 

// Be sure to use the named constants

// Handle the payment

// Say goodbye 

// Else

// Cancel the purchase 

return 0;
}

Answer 1

Change

TChoice << GetTicketType( &TChoice);

To Simple

GetTicketType( &TChoice);

Since TChoice << GetTicketType( &TChoice); is doing bitwise left shift operation it will expect an integer type after << .Your function is returning nothing(void) and thus causes an error.

Answer 2

It looks like you're getting an error on this line:

TChoice << GetTicketType( &TChoice);

You're calling GetTicketType and expecting to use the result. Is that really what you want to do, since it's a void function?