C++ 抽象类

acctabc.h

  1. #ifndef PRO1_ACCTABC_H
  2. #define PRO1_ACCTABC_H
  4. #include <iostream>
  5. #include <cstring>
  7. using namespace std;
  9. // Abstract Base Class
  10. class AcctABC {
  11. private:
  12.     enum {MAX = 35};
  13.     char fullName[MAX];
  14.     long acctNum;
  15.     double balance;
  16. protected:
  17.     const char * FullName()const { return fullName; }
  18.     long AcctNum()const { return acctNum; }
  19.     ios_base::fmtflags SetFormat()const ;
  21. public:
  22.     AcctABC(const char *s = "Nullbody", long an = -1, double bal = 0.0);
  23.     void Deposit(double amt);
  24.     virtual void Withdraw(double amt) = 0;
  25.     double Balance()const { return balance; };
  26.     virtual void ViewAcct()const = 0;
  27.     virtual ~AcctABC(){};
  28. };
  30. class Brass: public AcctABC{
  31. public:
  32.     Brass(const char*s = "Nullbody", long an = -1, double bal = 0.0);
  33.     virtual void Withdraw(double amt);
  34.     virtual void ViewAcct()const ;
  35.     virtual ~Brass();
  36. };
  38. class BrassPlus: public AcctABC{
  39. private:
  40.     double maxLoan;
  41.     double rate;
  42.     double owesBank;
  43. public:
  44.     BrassPlus(const char *s = "Nullbody", long an = -1, double bal = 0.0, double ml = 500, double r = 0.10);
  45.     BrassPlus(const Brass & ba, double ml = 500, double r = 0.1);
  46.     virtual void ViewAcct()const ;
  47.     virtual void Withdraw(double amt);
  48.     void ResetMax(double m){ maxLoan = m; }
  49.     void ResetRate(double r){ rate = r; }
  50.     void ResetOwes(){ owesBank = 0; }
  51. };
  53. #endif //PRO1_ACCTABC_H

acctabc.cpp

  1. #include "acctabc.h"
  2. #include <iostream>
  3. #include <cstring>
  5. using namespace std;
  7. AcctABC::AcctABC(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 AcctABC::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 AcctABC::Withdraw(double amt) {
  22.     balance -= amt;
  23. }
  25. ios_base::fmtflags AcctABC::SetFormat() const {
  26.     ios_base::fmtflags initialState = cout.setf(ios_base::fixed, ios_base::floatfield);
  27.     cout.setf(ios_base::showpoint);
  28.     cout.precision(2);
  29.     return initialState;
  30. }
  32. void Brass::Withdraw(double amt) {
  33.     if (amt < 0)
  34.         cout << "Withdrawal; amount must be positive;" << "withdrawal canceled.\n";
  35.     else if (amt <= Balance())
  36.         AcctABC::Withdraw(amt);
  37.     else
  38.         cout << "Withdrawal amount of $" << amt << " exceeds your balance.\n" << "Withdrawal canceled.\n";
  39. }
  41. void Brass::ViewAcct() const {
  42.     ios_base::fmtflags initialState = SetFormat();
  43.     cout << "Brass Client: " << FullName() << endl;
  44.     cout << "Account Number: " << AcctNum() << endl;
  45.     cout << "Balance: $ " << Balance() << endl;
  46.     cout.setf(initialState);
  47. }
  49. BrassPlus::BrassPlus(const char *s, long an, double bal, double ml, double r): AcctABC(s, an, bal) {
  50.     maxLoan = ml;
  51.     owesBank = 0.0;
  52.     rate = r;
  53. }
  55. BrassPlus::BrassPlus(const Brass &ba, double ml, double r):AcctABC(ba) {
  56.     maxLoan = ml;
  57.     owesBank = 0.0;
  58.     rate = r;
  59. }
  61. void BrassPlus::ViewAcct() const {
  62.     ios_base::fmtflags initialState = SetFormat();
  63.     cout << "BrassPlus Client: " << FullName() << endl;
  64.     cout << "Account Number: " << AcctNum() << endl;
  65.     cout << "Balance: $ " << Balance() << endl;
  66.     cout << "Maximum loan: $ " << maxLoan << endl;
  67.     cout << "Owed to Bank: $ " << owesBank << endl;
  68.     cout << "Loan Rate: " << 100 * rate << endl;
  69.     cout.setf(initialState);
  70. }
  72. void BrassPlus::Withdraw(double amt) {
  73.     ios_base::fmtflags initialState = SetFormat();
  74.     double bal = Balance();
  75.     if (amt <= bal)
  76.         AcctABC::Withdraw(amt);
  77.     else if (amt <= bal + maxLoan - owesBank){
  78.         double advance = amt - bal;
  79.         owesBank += advance * (1.0 + rate);
  80.         cout << "Bank advance: $ " << advance << endl;
  81.         cout << "Finance charge: $ " << advance * rate << endl;
  82.         Deposit(advance);
  83.         AcctABC::Withdraw(amt);
  84.     } else
  85.         cout << "Credit limit exceeded. Transaction cancelled.\n";
  86.     cout.setf(initialState);
  87. }