Newbie needing assistance on object construction, array of an object as function argument... - c++

cantide5ga wrote:

[original post re-arranged]

> I am a student beginning C++ (also new to Newsgroups as well) and am
> having a hell of a time understanding everything. My experience in OO
> and UML from a prior class provide an understanding of what C++ COULD
> do, but I can't seem to get past the coding aspect.
>
> The program below is one of my assignments that is the beginning of an
> Employee DB. It does what is asked, but not how it was asked:
>
<inserted remarks of OP>
>
> I *think* I should be able to somehow invoke a constructor to create
> an object for each employee (with relative name, title, wage, and
> hours data) but I can't wrap my head around the concept. The main
> obstacle here is having a unique object name created for each
> employee.

Actually, you don't need a unique name for each EmployeeData object.
Unless, that is, you consider things like 'employee[42]' to be a name as
well.

> After melting my brain for hours, I decided to just go with
> my default idea and have one object containing a user defined amount
> of arrays.
>
> According to the assignment:
> -Create and use a GetEmployee function that returns an employee
> object. This function will prompt the user to enter data, store that
> data in an object, and return the object to the calling function.

This requirement means effectively that GetEmployee can not be a regular
member of the EmployeeData class, because it is supposed to create such
objects.
That means you essentially have two, equally good, options: make it a
static member function, or make it a free-standing non-member function.

> -Create and use a function that displays a list of employees and their
> pay. This function will take an array of employee object as an
> argument.

The function that displays a list of employees should also not be a
member of EmployeeData. In a good OO design, members of a class should
primarily operate on the current object, not on a bunch of objects of
unspecified size.
You can, however, use a member function to display a single employee,
and call that function in a loop for displaying all of them.

>
> It sounds to me like I do indeed need to have an object for each
> employee, because the display function will take it as an argument!

That is right, you either need an array of EmployeeData objects, or
preferably you would used a std::vector<EmployeeData>.

> Oh man... any advice would be appreciated.
>
>
</insertion>

> //
>
**********************************************************************************************************************************
> #include <iostream>
> using std::cout;
> using std::cin;
> using std::endl;
>
> #include <string>
> using std::string;
> using std::getline;
>
> class EmployeeData
> {
> public:
> const static int number = 100;

Unlike some other languages, in C++ it is very common to have
functions/constants/etc that are not members of a class.
Lest move that declaration out of the class for now.

>
<snip>
> void putEmployee()
> {
> for (int n = 1; n <= staffNumber; n++)
> {
> cout << "Data for EMPLOYEE #" << n << endl;
>
> if (staffWage[n] > 20)
> staffName[n] = staffName[n] + "*";
>
> if (staffWage[n] * staffHours[n] > 800)
> staffName[n] = staffName[n] + "*";
>
> cout << "\nNAME\t: " << staffName[n];
> cout << "\nTITLE\t: " << staffTitle[n];
> cout << "\nPAY\t: $" << staffWage[n] *
> staffHours[n];
> }
> }
>
> private:
> string staffName[number];
> string staffTitle[number];
> double staffWage[number];
> double staffHours[number];

What is so different about writing arrays as members and writing
class EmployeeData {
string staffName;
string staffTitle;
double staffWage;
double staffHours;
} employees[number];

> int arrayData;
> int staffNumber;

These two really should not be members of EmployeeData.

<snip>
> };
>
> int main()
> {
> EmployeeData id0;
>
> id0.getEmployee();
> id0.putEmployee();
>
> return 0;
> }
>
> //
>
**********************************************************************************************************************************
As a reference, here is an alternative way to write the program.

#include <iostream>
#include <ostream>
#include <string>
#include <iterator>
#include <algorithm>
#include <vector>
using namespace std;

class Employee {
public:
Employee(string aName, string aTitle, double aHours, double aWage)
: name(aName), title(aTitle), hours(aHours), wage(aWage) {}
void Print(ostream& os) const
{
string printName = name;

if (wage > 20)
printName += '*';

if ((wage * hours) > 800)
printName += '*';

os << "\nNAME\t: " << printName;
os << "\nTITLE\t: " << title;
os << "\nPAY\t: $" << wage * hours;
}
private:
string name;
string title;
double hours;
double wage;
};

Employee GetEmployee()
{
string name;
string title;
double hours;
double wage;

cout << "Employee NAME\t: ";
getline(cin, name);

cout << "Employee TITLE\t: ";
getline(cin, title);

cout << "Employee WAGE\t: ";
cin >> wage;

cout << "Employee HOURS\t: ";
cin >> hours;

return Employee(name, title, hours, wage);
}

ostream& operator<<(ostream& os, const Employee& emp)
{
emp.Print(os);
return os;
}

void PrintEmployees(const vector<Employee>& employees)
{
copy(employees.begin(),
employees.end(),
ostream_iterator<Employee>(cout, ""));
}

int main()
{
vector<Employee> employees;
int staffSize;

cout << "Please enter number of employees (max. 100):";
cin >> staffSize;
cin.ignore( 1, '\n' );

for (int i=0; i<staffSize; i++)
{
employees.push_back(GetEmployee());
}

PrintEmployees(employees);
}

Bart v Ingen Schenau
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