C++ 多态公有继承

brass.h

  1. #ifndef PRO1_BRASS_H
  2. #define PRO1_BRASS_H
  5. class Brass {
  6. private:
  7.     enum {MAX = 35};
  8.     char fullName[MAX];
  9.     long acctNum;
  10.     double balance;
  11. public:
  12.     Brass(const char* s = "Nullbody", long an = -1, double bal = 0.0);
  13.     void Deposit(double amt);
  14.     virtual void Withdraw(double amt);
  15.     double Balance()const ;
  16.     virtual void ViewAcct()const ;
  17.     virtual ~Brass(){};
  18. };
  20. class BrassPlus : public Brass{
  21. private:
  22.     double maxLoan;
  23.     double rate;
  24.     double owesBank;
  25. public:
  26.     BrassPlus(const char* s = "Nullbody", long an = -1, double bal = 0.0, double ml = 500, double r = 0.10);
  27.     BrassPlus(const Brass & ba, double ml = 500, double r = 0.1);
  28.     virtual void ViewAcct()const ;
  29.     virtual void Withdraw(double amt);
  30.     void ResetMax(double m){ maxLoan = m; }
  31.     void ResetRate(double r){ rate = r; }
  32.     void ResetOwes(){ owesBank = 0; }
  33. };
  35. #endif //PRO1_BRASS_H

brass.cpp

  1. #include "brass.h"
  2. #include <iostream>
  3. #include <cstring>
  5. using namespace std;
  7. Brass::Brass(const char *s, long an, double bal) {
  8.     strncpy(fullName, s, MAX - 1);
  9.     fullName[MAX - 1] = '\0';
  10.     acctNum = an;
  11.     balance = bal;
  12. }
  14. void Brass::Deposit(double amt) {
  15.     if (amt < 0)
  16.         cout << "Negative deposit not allowed: " << "deposit is cancelled.\n";
  17.     else
  18.         balance += amt;
  19. }
  21. void Brass::Withdraw(double amt) {
  22.     if (amt < 0)
  23.         cout << "Withdrawal amount must be positive: " << "withdrawal canceled.\n";
  24.     else if (amt <- balance)
  25.         balance -= amt;
  26.     else
  27.         cout << "Withdrawal amount of $" << amt << " exceeds your balance.\n" << "Withdrawal canceled.\n";
  28. }
  30. double Brass::Balance() const {
  31.     return balance;
  32. }
  34. void Brass::ViewAcct() const {
  35.     ios_base::fmtflags initialState = cout.setf(ios_base::fixed, ios_base::floatfield);
  36.     cout.setf(ios_base::showpoint);
  37.     cout.precision(2);
  38.     cout << "Client: " << fullName << endl;
  39.     cout << "Account Number: " << acctNum << endl;
  40.     cout << "Balance: $" << balance << endl;
  41.     cout.setf(initialState);
  42. }
  44. BrassPlus::BrassPlus(const char *s, long an, double bal, double ml, double r):Brass(s, an, bal) {
  45.     maxLoan = ml;
  46.     owesBank = 0.0;
  47.     rate = r;
  48. }
  50. BrassPlus::BrassPlus(const Brass &ba, double ml, double r):Brass(ba) {
  51.     maxLoan = ml;
  52.     owesBank = 0.0;
  53.     rate = r;
  54. }
  56. void BrassPlus::ViewAcct() const {
  57.     ios_base::fmtflags initialState = cout.setf(ios_base::fixed, ios_base::floatfield);
  58.     cout.setf(ios_base::showpoint);
  59.     cout.precision(2);
  61.     Brass::ViewAcct();
  62.     cout << "Maximum loan: " << maxLoan << endl;
  63.     cout << "Owed to bank: " << owesBank << endl;
  64.     cout << "Loan Rate: " << 100 * rate << "%\n";
  65.     cout.setf(initialState);
  66. }
  68. void BrassPlus::Withdraw(double amt) {
  69.     ios_base::fmtflags initialState = cout.setf(ios_base::fixed, ios_base::floatfield);
  70.     cout.setf(ios_base::showpoint);
  71.     cout.precision(2);
  73.     double bal = Balance();
  74.     if (amt <= bal)
  75.         Brass::Withdraw(amt);
  76.     else if (amt <= bal + maxLoan - owesBank){
  77.         double advance = amt - bal;
  78.         owesBank += advance*(1.0 + rate);
  79.         cout << "Bank advance: $ " << advance << endl;
  80.         cout << "Finance charge: $ " << advance * rate << endl;
  81.         Deposit(advance);
  82.         Brass::Withdraw(amt);
  83.     } else
  84.         cout << "Credit limit exceeded. Transaction cancelled.\n";
  85.     cout.setf(initialState);
  86. }

main.cpp

  1. #include <iostream>
  2. #include "module7_polymorphism/brass.h"
  4. using namespace std;
  6. // 多态公有继承
  7. void useBrass(){
  8.     Brass Piggy("Procelot Pigg", 381299, 4000.00);
  9.     BrassPlus Hoggy("Horatio Hogg", 382288, 3000.00);
  10.     Piggy.ViewAcct();
  11.     cout << endl;
  12.     Hoggy.ViewAcct();
  13.     cout << endl;
  14.     cout << "Depositing $1000 into the Hogg Account: \n";
  15.     Hoggy.Deposit(1000.00);
  16.     cout << "New balance: $ " << Hoggy.Balance() << endl;
  17.     cout << "Withdrawing $4200 from the Pigg Account:\n";
  18.     Piggy.Withdraw(4200.00);
  19.     cout << "Pigg account balance: $ " << Piggy.Balance() << endl;
  20.     cout << "Withdrawing $4200 from the Hogg Account:\n";
  21.     Hoggy.Withdraw(4200.00);
  22.     Hoggy.ViewAcct();
  23. }
  25. int main() {
  26.     useBrass();
  27.     return 0;
  28. }