c++ - 方法未更新int

Question

#include <iostream>
using namespace std;

class CreditCard {
  public:

  int balance;
  float points;
  

  CreditCard () {
    balance = 0;
    points = 0;
  }

  void charge() {
    int charge;
    cout << "Amount to charge:" << endl;
    cin >> charge;
    cout << endl;
    points = points + (charge/100.);
    balance = balance + charge;
    return;
  }

  void payment() {
    int payment;
    cout << "Amount to pay:" << endl;
    cin >> payment;
    cout << endl;
    balance = balance - payment;
    return;
  }

  void currentBal() {
    cout << endl;
    cout << "Balance: " << balance << endl;
    cout << "Points: " << points << endl;
    return;
  }
  
};

int main() {  

  int userChoice;
  bool run = true;

  while (run == true) {
  cout << "Would you like to:" << endl;
  cout << "1) Charge" << endl;
  cout << "2) Make a payment" << endl;
  cout << "3) See current balance" << endl;
  cout << "4) Quit" << endl;
  cin >> userChoice;

  CreditCard card1;
  
  switch (userChoice) {
    case 1:
      card1.charge();
      break;
    case 2:
      card1.payment();
      break;
    case 3:
      card1.currentBal();
      break;
    case 4:
      run = false;
      break;
  }
  }
    
}

我有这个作业来练习方法和类。该程序将打印带有某些选项的菜单。当我选择选项1并设置余额，然后选择选项3来打印余额时，余额保持为0。我已经在计费方法中放入了打印语句，表明余额已更新，但是一旦我调用currentBal方法，余额重新设置为0。

Answer 1

您的CreditCard card1;在while循环中，循环的每次迭代都会创建一张新卡。