c++ - Small question concerning redefining member functions -

I am trying to re-define two member tasks with the definition of their parent.
I do not know whether I am right or not, but there are some errors in my code and I do not know.

Some headers:

  class account {public: account (double); Zero credit balance (double); Zero debit balan (double); Double getBalance () console; Protected: double balance; }; Class Checking Account: Public Account {Public: Checking Account (Double, Double); Zero duty credit balance (double); Zero fee debitbelens (double); Private: Double charge = 10; };  

Part of the relevant CPP file:

  zero account :: credit balance (double plus) {if (plus> left) = + plus; And cout & lt; & Lt; "Negative can not be negative."; } Zero account :: debit balance (double minus) {if (zero and lieutenant = = balance) balance - = zero; And cout & lt; & Lt; "Debit amount is greater than account balance."; } Zero Checking Rights :: Fee Credit Balance (Double Plus) {If (plus> 0) {Balance = + Plus; Balance - = fee; } And cout & lt; & Lt; "Negative can not be negative."; } Zero checkingAccount :: Fee DebitBelance (double minus) {if (minus and lieutenant = = balance) {balance - = zero; Balance - = fee; } And cout & lt; & Lt; "Debit amount is greater than account balance."; }  

update:

I added it:

  class account {public: account (double); Virtual zero credit balance (double); Virtual zero debit balance (double); Double getBalance () console; Protected: double balance; };  

Now I get an error: Virtual Outward Declaration

I can use the example of properly starting the fee properly.

Edit 2:

I have tried to change the constructor line for this:

  checking account :: checking account (double intelligible, double-fi ): Account (Initial), Fees (FI) {if (InitBal & lt; 0) initBal = 0; Balance = initBal; Serie Lieutenant; & Lt; "The initial balance was invalid."; If (Fiat & Lt; 0) Fei = 0; Fee = FI; }  

is not working, I'm going to work around with changing the syntax on the part of the file (file). I do not know if anyone will respond to it.

If it is intended that the versions that use the fees for the investigation cases, they say , You want to use virtual methods.

A virtual method is decalared (at least in the base class) as a "virtual" method, and its name is identical and signature in some derivative classes. When called a virtual method, it will call the "highest derivative" version for example.

To do this, simply declare "zero credit balloon (double)"; "And" Debit Debit Balance ";" Virtual "(i.e." virtual zero credit equal (double) "and" virtual zero debitability (double); "Then the" fee credit balance "and" fee debit balance "in the checking ACC" CreditBlobense "and" DebitBalance ".

Edit: Simple example.

  class base {public: declare base (int x); // so that the derivative Classes called hello (); it is called virtual zero; conserved: int x;} square root Pages: Public base {public: derived (int x, int y); // overide base :: sayHello (). Here the virtual keyword is optional Virtual Zero say hello (); protected: x (x) {} Concluded :: Useless (int x, x, x, x, x, x, x, x, x, int y): Base (x), y (y) {} zero base: say hello () {std :: cout &  Lite < :: endl;} Vain derivative: say hello () {std :: cout << lt; "Hello from!" & Lt; std :: andl; std :: COAT & lt; ; "X =" & lt; & Lt; X & LT; & Lt; "Y =" & lt; & Lt; Y & lt; & Lt; Std :: endl; } Int main () {base a (5); A.sayHello (); // "Hello from base! ..." derived b (10, -20); B.sayHello (); // "Derived from Hello! ..." Base * c = & amp; Amp; B; // put the pointer in B, also reference- c-> Say hello // "Hello from fear! ..." because it is a derivative example, this is a base variable}  

Then you can get it again from derivative (Class DerivedAgain: public Derived) and then overload the work too.

You can also get many subclasses from the base, which can have its override for each of the virtual methods, like I did for the derived class.

EDIT2: For example, the variable has been added and how to use the initial list to start the base class and member variable.