compiling error with classes

I'm getting an error with my class program. Does anyone know how to fix this?

#include <iostream>
using namespace std;


//class for a bank certificate of deposit:
class CDAccount
{
public:
CDAccount(double rate_fraction, double interest, double account);
CDAccount();
void get_data();
void putout();
void calculate();
private:
double balance;
double interest_rate;
int term;//months until maturity
};


CDAccount account;


int main( )
{
account.get_data();
account.calculate();
account.putout();

return 0;
}

void CDAccount::get_data()
{
cout << "Enter account balance: $";
cin >>account.balance;
cout << "Enter account interest rate: ";
cin >> account.interest_rate;
cout << "Enter the number of months until maturity\n"
<< "(must be 12 or fewer months): ";
cin >>account.term;
}

void CDAccount::calculate()
{
double rate_fraction, interest;
rate_fraction = account.interest_rate/100.0;
interest = account.balance*rate_fraction*(account.term/12.0);
account.balance = account.balance + interest;
}

void CDAccount::putout()
{


cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(2);

cout << "When your CD matures in "
<< account.term << " months,\n"
<< "it will have a balance of $"
<< account.balance << endl;

}

/*
--------------------Configuration: seven - Win32 Debug--------------------
Linking...
seven.obj : error LNK2001: unresolved external symbol "public: __thiscall CDAccount::CDAccount(void)" (??0CDAccount@@QAE@XZ)
Debug/seven.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

seven.exe - 2 error(s), 0 warning(s)
*/

Implement constructors for CDAccount.

thank you. i'm suppose to use a default constructor, does that make a difference?

Quote:

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thank you. i'm suppose to use a default constructor, does that make a difference?

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If you are going to use a default constructor then you don't have to specify one, the compiler does it for you

Uncomment

Code:

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CDAccount(double rate_fraction, double interest, double account);
CDAccount();

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in the class definition.

Quote:

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Originally posted by ripper079

If you are going to use a default constructor then you don't have to specify one, the compiler does it for you

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I would recommend writing your own, then you know exactly whats going on every time. And sometimes you dont want all those data members set to 0 :)

Quote:

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Originally posted by endo

I would recommend writing your own, then you know exactly whats going on every time. And sometimes you dont want all those data members set to 0

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I totaly agree, but a closer look at the member-function get_data(), initialization (made by constructor) seems redundant. I know that there is a potential risk that the object is beeing used before initialized but the first code line i main is actually an invoke to the member-function get_data(). This is a design issue that the programmer must consider.

zeni3773
But if you want to do it the "right" (my) way I would definitly write the implementation for

Code:

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CDAccount(double rate_fraction, double interest, double account);
CDAccount();

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This way you can be sure that all data-members have been properly initialized and at the same time add more flexibility to yours class.

thank you both for your help! i made a few changes to the program and it's working now!