辅导CMPSC121 Structs辅导留学生C/C++

C++，Struct。

Objectives

After this lab assignment, students should be able to:

• Declare and initialize C++ structs
• Implement designs using structs

Instructions

In this lab, we will create an abstraction of a vending machine in C++, using structs to describe each item in the machine, and a vector to maintain a list of all the items in the machine.
Use the following struct declaration for vending machine items:

1
2
3
4
5
6

struct item #123;
  string name; // name of the item
  int code;    // numerical code entered to select the item
  float price; // price per unit of the item
  int stock;   // number of items available in the machine
#125;;

Use the following vector declaration for the vending machine:

1
2

int main() #123;
  vectorlt;itemgt; vendingMachine;

Complete the three following function headers shown below:

1
2

float totalValue(vectorlt;itemgt; vendingMachine)
// return the total value of all items in the vending machine

1
2
3
4

void stock(string name, int count, vectorlt;itemgt; amp;vendingMachine)
// add "count" items to the vending machine with the given "name"
// if the item to be added was not already in the machine, prompt the user for its code and price (in dollars)
// if the code is already being used by the machine, prompt the user for a different code

1
2
3
4
5
6
7

void purchase(float balance, int code, vectorlt;itemgt; amp;vendingMachine)
// make a purchase from the vending machine
// "balance" is the amount of money (in dollars) inserted
// "code" is the item to purchase
// if "code" is not mapped to an item, display error message
// if the item is more expensive than "balance", display error message
// if purchase is successful, display change to be returned in dollars and update the stock of that item.

Testing the Functions

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

int main() #123;
  vectorlt;itemgt; vendingMachine;
  stock("Doublemint Gum", 1, vendingMachine);
  cout lt;lt; "-------------------" lt;lt; endl;
  purchase(.50, 100, vendingMachine);
  cout lt;lt; "-------------------" lt;lt; endl;
  stock("Chocolate Chip Cookies", 10, vendingMachine);
  cout lt;lt; "-------------------" lt;lt; endl;
  stock("Chocolate Chip Cookies", 5, vendingMachine);
  cout lt;lt; "-------------------" lt;lt; endl;
  purchase(.75, 100, vendingMachine);
  cout lt;lt; "-------------------" lt;lt; endl;
  purchase(1.00, 100, vendingMachine);
  cout lt;lt; "This vending machine now has $" totalValue(vendingMachine) lt;lt; fixed lt;lt; setprecision(2) lt;lt; " worth of items" lt;lt; endl;
#125;

Sample Output

The item you are adding, Doublemint Gum, was not in the machine. Please enter the following information for this item Code: 100 Price: $0.75 You have added 1 units of Doublemint Gum. Now there are 1 units in the machine ------------------ You have selected to purchase Doublemint Gum, which costs $0.75 Your balance is $0.50. Not enough money! ------------------ The item you are adding, Chocolate Chip Cookies, was not in the machine. Please enter the following information for this item Code: 100 That code is already being used by Doublemint Gum. Enter a new code: 101 Price: $2.00 You have added 10 units of Chocolate Chip Cookies. Now there are 10 units in the machine ------------------ You have added 5 units of Chocolate Chip Cookies. Now there are 15 units in the machine ------------------ You have selected to purchase Doublemint Gum, which costs $0.75 Thank you for purchasing! Your change is: $0.00 ------------------ Item not found! ------------------ This vending machine now has $30.00 worth of items Press any key to continue ... 

Submission

Call your program VendingMachine.cpp. This file must contain all of the following items:

• Completed function definitions:
  • totalValue()
  • purchase()
  • stock()
• Declaration of struct item
• main() function with same code found in the “Testing the Functions” section above
• A sample output of your program, like shown in the “Sample Output” section above (the output does not have to match exactly)

Submit VendingMachine.cpp to Canvas before the deadline.