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

C

cantide5ga

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:

//
**********************************************************************************************************************************
#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;

void getEmployee()
{
getStaffNumber();

for (int n = 1; n <= staffNumber; n++)
{
cout << "Input data for EMPLOYEE #" << n << endl;

arrayData = n;

getStaffName();
getStaffTitle();
getStaffWage();
getStaffHours();

cin.ignore( 1, '\n' );
}
}

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];
int arrayData;
int staffNumber;

int getStaffNumber()
{
int number;

cout << "Please enter number of employees (max. 100): ";
cin >> number;

staffNumber = number;

cin.ignore( 1, '\n' );

return staffNumber;
}

string getStaffName()
{
string name;

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

staffName[arrayData] = name;

return staffName[arrayData];
}

string getStaffTitle()
{
string title;

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

staffTitle[arrayData] = title;

return staffTitle[arrayData];
}

double getStaffWage()
{
double wage;

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

staffWage[arrayData] = wage;

return staffWage[arrayData];
}

double getStaffHours()
{
double hours;

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

staffHours[arrayData] = hours;

return staffHours[arrayData];
}
};

int main()
{
EmployeeData id0;

id0.getEmployee();
id0.putEmployee();

return 0;
}
//
**********************************************************************************************************************************

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. 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.
-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.

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!
Oh man... any advice would be appreciated.
 
O

osmium

cantide5ga said:
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:
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. 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.
-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.

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!
Oh man... any advice would be appreciated.

You misunderstand the assignment. GetEmployee is a "free standing" (for
lack of a better word) function. It's purpose is to interact with the user
and create an Emloyee object, it is not a part of the employee class as you
have it.
 
J

Jim Langston

cantide5ga said:
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:

//
**********************************************************************************************************************************
#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;

void getEmployee()
{
getStaffNumber();

for (int n = 1; n <= staffNumber; n++)
{
cout << "Input data for EMPLOYEE #" << n << endl;

arrayData = n;

getStaffName();
getStaffTitle();
getStaffWage();
getStaffHours();

cin.ignore( 1, '\n' );
}
}

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];
int arrayData;
int staffNumber;

int getStaffNumber()
{
int number;

cout << "Please enter number of employees (max. 100): ";
cin >> number;

staffNumber = number;

cin.ignore( 1, '\n' );

return staffNumber;
}

string getStaffName()
{
string name;

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

staffName[arrayData] = name;

return staffName[arrayData];
}

string getStaffTitle()
{
string title;

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

staffTitle[arrayData] = title;

return staffTitle[arrayData];
}

double getStaffWage()
{
double wage;

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

staffWage[arrayData] = wage;

return staffWage[arrayData];
}

double getStaffHours()
{
double hours;

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

staffHours[arrayData] = hours;

return staffHours[arrayData];
}
};

int main()
{
EmployeeData id0;

id0.getEmployee();
id0.putEmployee();

return 0;
}
//
**********************************************************************************************************************************

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. 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.
-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.

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!
Oh man... any advice would be appreciated.

Since this is homework, I'll not give you complete code, but you have shown
a tremendous amount of effort, so I'll pretty much show you how to do it.
Untested code: Note that mainline is just showing a rudimentary way of
input, etc... you should use proper error checking, etc...

class EmployeeData
{
public:
EmployeeData( const std::string& Name, const std::string& Title ):
Name_( Name ), Title_( Title ) {}
std::string Name() { return Name_; }
std::string Title() { return Title_; }
private:
std::string Name_;
std::string Title_;
};

int main()
{
std::vector<EmplyeeData> Data;

std::string Name;
std::string Title;
std::cout >> "Enter Employee Name: ";
while ( std::getline( std::cin, Name ) )
{
std::cout >> "Enter Emplee Title: ";
if ( std::getline( std::cin, Title ) )
{
Data.push_back( EmployeeData( Name, Title ) );
}
}

// At this point Data contains Employee's if they were input.
for ( int i = 0; i < Data.size(); ++i )
{
std::cout << "Name: " << Data.Name() << "\n";
std::cout << "Title: " << Data.Title() << "\n\n";
}

}

I pushed instances of EmploeeData onto a vector. At this point three is one
EmployeeData instance for each employee that was entered. There are a few
ways to go through the employees, I'm showing one way, you can also use
iterators. You may also perfer to use a std::map keyed by EmploeeName or
such.
 
C

cantide5ga

You misunderstand the assignment. GetEmployee is a "free standing" (for
lack of a better word) function. It's purpose is to interact with the user
and create an Emloyee object, it is not a part of the employee class as you
have it.

So a separate class with its own functions?
 
V

Victor Bazarov

cantide5ga said:
[..]
You misunderstand the assignment. GetEmployee is a "free standing"
(for lack of a better word) function. It's purpose is to interact
with the user and create an Emloyee object, it is not a part of the
employee class as you have it.

So a separate class with its own functions?

A "free standing" function is not a member of any class. Like 'main'.

V
 
O

osmium

cantide5ga said:
So a separate class with its own functions?

No. just a function. perhaps like this

Emp& get_emp()
// interact with user. create an employee and return it.
 
V

Victor Bazarov

osmium said:
No. just a function. perhaps like this

Emp& get_emp()
// interact with user. create an employee and return it.

Just a thought: if a function is to _create_ an object, it should
most likely either return a pointer to a dynamically created one,
or return the object by value. Returning a reference to non-const
object often presumes the object existed before the function was
called.

V
 
C

cantide5ga

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:
//
**********************************************************************************************************************************
#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;
void getEmployee()
{
getStaffNumber();
for (int n = 1; n <= staffNumber; n++)
{
cout << "Input data for EMPLOYEE #" << n << endl;
arrayData = n;

cin.ignore( 1, '\n' );
}
}
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];
int arrayData;
int staffNumber;
int getStaffNumber()
{
int number;
cout << "Please enter number of employees (max. 100): ";
cin >> number;
staffNumber = number;
cin.ignore( 1, '\n' );
return staffNumber;
}
string getStaffName()
{
string name;
cout << "Employee NAME\t: ";
getline(cin, name);
staffName[arrayData] = name;
return staffName[arrayData];
}
string getStaffTitle()
{
string title;
cout << "Employee TITLE\t: ";
getline(cin, title);
staffTitle[arrayData] = title;
return staffTitle[arrayData];
}
double getStaffWage()
{
double wage;
cout << "Employee WAGE\t: ";
cin >> wage;
staffWage[arrayData] = wage;
return staffWage[arrayData];
}
double getStaffHours()
{
double hours;
cout << "Employee HOURS\t: ";
cin >> hours;
staffHours[arrayData] = hours;
return staffHours[arrayData];
}
};
int main()
{
EmployeeData id0;

return 0;
}
//
**********************************************************************************************************************************
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. 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.
-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.
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!
Oh man... any advice would be appreciated.

Since this is homework, I'll not give you complete code, but you have shown
a tremendous amount of effort, so I'll pretty much show you how to do it.
Untested code: Note that mainline is just showing a rudimentary way of
input, etc... you should use proper error checking, etc...

class EmployeeData
{
public:
EmployeeData( const std::string& Name, const std::string& Title ):
Name_( Name ), Title_( Title ) {}
std::string Name() { return Name_; }
std::string Title() { return Title_; }
private:
std::string Name_;
std::string Title_;

};

int main()
{
std::vector<EmplyeeData> Data;

std::string Name;
std::string Title;
std::cout >> "Enter Employee Name: ";
while ( std::getline( std::cin, Name ) )
{
std::cout >> "Enter Emplee Title: ";
if ( std::getline( std::cin, Title ) )
{
Data.push_back( EmployeeData( Name, Title ) );
}
}

// At this point Data contains Employee's if they were input.
for ( int i = 0; i < Data.size(); ++i )
{
std::cout << "Name: " << Data.Name() << "\n";
std::cout << "Title: " << Data.Title() << "\n\n";
}

}

I pushed instances of EmploeeData onto a vector. At this point three is one
EmployeeData instance for each employee that was entered. There are a few
ways to go through the employees, I'm showing one way, you can also use
iterators. You may also perfer to use a std::map keyed by EmploeeName or
such.


Thanks to all of you. Will spend the rest of the night playing with
the suggestions. Jim, I'll be dissecting your code to be sure I
understand a lot of it, special thanks to you.

Only thing I am worried about is the scope here (not OO scope btw).
I'd rather stay within the realm of our studies 'thus far' to achieve
what I need to. The extra effort will be made to understand it all.
 

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