标号5中的格式指定符{0,10:0.00}，表明在10个打印位宽度中右对齐数额，并四舍五入到小数点后两位，且至少在小数点前有一位数。
Deposit类型直接依赖于Transaction与TransactionType类型，所以在Deposit的编译期间，必须确保可访问到这两者的程序集。但是，编译器可能会发出一个警告，表示TransactionType已经被引入了两次，一次是直接，而另一次是间接地通过Transaction，在此，可安全地忽略此警告信息。
Withdrawal类定义在例4中，而Transfer类定义在例5中。
例4：
using namespace System;
public ref class Withdrawal sealed : Transaction
{
Decimal amount;
int fromAccount;
public:
Withdrawal(double amount, int fromAccount) : Transaction(TransactionType::Withdrawal)
{
WithdrawalAmount = Decimal(amount);
WithdrawalFromAccount = fromAccount;
}
Withdrawal(Decimal amount, int fromAccount) : Transaction(TransactionType::Withdrawal)
{
WithdrawalAmount = amount;
WithdrawalFromAccount = fromAccount;
}
property Decimal WithdrawalAmount
{
Decimal get() { return amount; };
private:
void set(Decimal value) { amount = value; };
}
property int WithdrawalFromAccount
{
int get() { return fromAccount; };
private:
void set(int value) { fromAccount = value; };
}
void PostTransaction()
{
Console::WriteLine("{0} -- {1}", DateTimeOfTransaction, this);
}
virtual String^ ToString() override
{
return String::Format("With: {0,10:0.00} {1,10}",
WithdrawalAmount, WithdrawalFromAccount);
}
}; |
例5：
using namespace System;
public ref class Transfer sealed : Transaction
{
Decimal amount;
int fromAccount;
int toAccount;
public:
Transfer(double amount, int fromAccount, int toAccount): Transaction(TransactionType::Transfer)
{
TransferAmount = Decimal(amount);
TransferFromAccount = fromAccount;
TransferToAccount = toAccount;
}
Transfer(Decimal amount, int fromAccount, int toAccount): Transaction(TransactionType::Transfer)
{
TransferAmount = amount;
TransferFromAccount = fromAccount;
TransferToAccount = toAccount;
}
property Decimal TransferAmount
{
Decimal get() { return amount; };
private:
void set(Decimal value) { amount = value; };
}
property int TransferFromAccount
{
int get() { return fromAccount; };
private:
void set(int value) { fromAccount = value; };
}
property int TransferToAccount
{
int get() { return toAccount; };
private:
void set(int value) { toAccount = value; };
}
void Transfer::PostTransaction()
{
Console::WriteLine("{0} -- {1}", DateTimeOfTransaction, this);
}
virtual String^ ToString() override
{
return String::Format("Xfer: {0,10:0.00} {1,10} {2,10}",
TransferAmount, TransferToAccount, TransferFromAccount);
}
}; |
虽然三个PostTransaction的实现是同样的，但在真实的处理系统中，这是不可能发生的。
测试程序
例6是测试交易类型的程序，它会创建一个具体交易类型的数组、遍历此数组、调用每个元素的PostTransaction函数。插1是某次执行后的输出，默认使用的是美国式的时间格式，即为，月、日、年、12小时制。
例6：
using namespace System;
int main()
{
array^ list = gcnew array {
gcnew Deposit(123.05, 12345),
gcnew Transfer(Decimal::Parse("1256.40"), 1111, 222),
gcnew Withdrawal(34.54, 232323),
gcnew Deposit(56.12, 14321)
};
for each (Transaction^ t in list)
{
t->PostTransaction();
}
} |
插1：例6某次执行后的输出
3/20/2005 12:36:16 AM -- Dep: 123.05 12345
3/20/2005 12:36:18 AM -- Xfer: 1256.40 222 1111
3/20/2005 12:36:19 AM -- With: 34.54 232323
3/20/2005 12:36:21 AM -- Dep: 56.12 14321 | |
