C++ Class Member Function change the member field value

#include <cstdio>
#include <cstdlib>
#include <iostream>

using namespace std;
class MyAccount/*from  w w w. j ava  2s.  co m*/
{
  public:
    double deposit(double amount)
    {
        balance += amount;
        return balance;
    }

    unsigned int accountNumber;
    double  balance;
};

int main(int nNumberofArgs, char* pszArgs[])
{
    MyAccount s;
    s.accountNumber = 123456;
    s.balance = 0.0;

    cout << "Depositing 10 to account " << s.accountNumber << endl;
    s.deposit(10);
    cout << "Balance is " << s.balance << endl;

    return 0;
}