C++ Semantic issue: "'use of undeclared identifier 'balance'"

Question

I am new to C++ and using Xcode and I am having an issue, in my main .cpp file Account.cpp the code is-

#include <iostream>

using namespace std;
#include "Account.h"
Account::Account()

{
    double balance=0;
    balance=0;
}
Account getbalance()
{
    return balance;
}

void deposit(double amount)
{
    balance+=amount;
}
void withdraw(double amount)
{
    balance-=amount;
}
void addInterest(double interestRate)
{
    balance=balance*(1+interestRate);
}

I think I missed something but I'm not sure where, any help would be appreciated thank you.

**The header file Account.h is-

#include <iostream>
using namespace std;
class Account
{
private:
    double balance;
public:
    Account();
    Account(double);
    double getBalance();
    void deposit(double amount);

    void withdraw(double amount);
    void addInterest(double interestRate);
};

Answer 1

Write the constructor the following way

Account::Account()
{
    balance = 0.0;
}

I suppose that balance is a data member of type double of class Account.

Or you can write

Account::Account() : balance( 0.0 ) {}

And all these function definitions if the functions are class member functions must look at least like

double Account::getBalance()
{
    return balance;
}

void Account::deposit(double amount)
{
    balance+=amount;
}
void Account::withdraw(double amount)
{
    balance-=amount;
}
void Account::addInterest(double interestRate)
{
    balance=balance*(1+interestRate);
}

Also it seems that you forgot to define the constructor with a parameter.

Account::Account( double initial_balance ) : balance( initial_balance ) {}