account class

[Mahnoor_1]

hey guys Im here again :P
Here is my code for bank account class..

#include<iostream>
#include<iomanip>

using namespace std;

class account
{
    private:
        int account_balance;
    public:
        account(int acc) //constructor
        {
            if(acc>=0)
            {
             account_balance=acc;
            }
            else
            {
            account_balance=0;          
            cout<<"initial balance is invalid"<<endl;
            }
        }

        int credit(int ammount)  //credit member function
        {
        return account_balance+ammount;
        }

        int debit(int deb)  //debit member function
        {
            if(deb<=account_balance)
            {
            return account_balance-deb;
            }
            else
            {
            return account_balance;
            cout<<"Debit ammount exceeded account balance"<<endl;   
            }
        }

};

/* main body 
*/
int main()
{
 int acc,ammount,deb;
 cout<<"enter account balance"<<endl;
 cin>>acc;
 account obj(acc);
 cout<<"enter credit ammount"<<endl;
 cin>>ammount;
 cout<<"after adding credit ammount, your account balance is:"<<setw(5)<<obj.credit(ammount)<<endl;
 cout<<endl<<"enter debit ammount"<<endl;
 cin>>deb; 
 cout<<"after deducting debit ammount, your account balance is:"<<setw(5)<<obj.debit(deb)<<endl;

 return 0;
}

there is no any error in my code but logical error. Problem is when i enter credit ammount it does not adds it into account balance. And when i enter debit ammount it does not deducts it from account balance as well. Anyone please help.Im stuck here..

[Moschops]

The account_balance is what you're trying to change, right?

So here are all the lines in your code where the account_balance is changed:

Line 15: account_balance=acc;
Line 19: account_balance=0;

So where in your function credit do you think you are changing account_balance?

[Mahnoor_1]

yes, in line 26 :

return account_balance+ammount;

but it is not adding the ammount in account_balance.

[Mahnoor_1]

There is some kind of logical error here which i am not figuring out.
I am passing the ammount in parameter to member func. credit ...and i know the method I used is obvious but why the answer is not right? :(

[Moschops]

Line 26 does NOT change the value of account_balance. Let's take a look at it.

return account_balance+ammount;

So what's happening on the right? You're taking a number, account_balance, and you're taking another number, ammount, and you're adding them together to create a new number. Did you change the value of account_balance? No. You just used it in your addition. Did you change the value of ammount? No, you just used it in your addition.

Here is how to change the value of a variable:
x = 4; // this changes the value of x

So here is how to change the value of account_balance:
account_balance = something; // this changes the value of account_balance to be the same as something

[Mahnoor_1]

:o Moschops You're amazing ..
I knew there is some logical mistake.I tried this:

    int credit(int ammount)  //credit member function
        {
        return account_balance=account_balance+ammount;
        }

and it actually changed the value of account_balance :D
thank you..

[Moschops]

A far less confusing way to write that would be

int credit(int ammount)  //credit member function
{
  account_balance = account_balance+ammount;
  return account_balance;
}

although I think you should have a separate function entirely for fetching the account balance. What if someone just wants to know what their account balance is?

[Mahnoor_1]

Oh yeah I'm still working on it..There are loads of changing to do.

[Mahnoor_1]

What if I use switch in main() because may be user either tells credit ammount or debit ammount?