Pointer to Structure of Arrays

[GG96]

Hi guys, I need help with this programming assignment. I am supposed to modify a previous program where we use two array of structs to hold various employee data from two files containing this data. One file holds the employees first name, last name, ID number, and payrate. The other file contains the employee ID number and hours worked. The data is matched and outputted to a third file. I managed to complete the previous program without any issues, but this new assignment requires us to modify the program to give dynamically allocated memory to the array using pointers. Visual Studio keeps telling me that the expression must contain a pointer type anywhere where I use "dataArray[?]->structmember"

#include <iostream>
#include <string>
#include <fstream>
#include <iomanip>

using namespace std;

struct File1
{
	string firstName;
	string lastName;
	string employeeNumber;
	int hours;
	float payrate;
};

struct File2
{
	string employeeNumber;
	int hours;
};


int getData1(string, File1*);
//Precondition: The first parameter is the name of a file filled with employee data, the second is a pointer to a structure array used to hold the employee data
//Postcondition: Opens the user specified file and writes various employee data to a structure array

int getData2(string, File2*);
//Precondition: The first parameter is the name of a file containing the number of hours an employee worked, the second is a pointer to a structure array used to hold the hours from the file
//Postcondition: Opens the user specified file and writes the number of hours each employee worked to a structure array

void selectionSort1(File1*, int);
//Precondition: The first parameter is a pointer to a structure array used to hold the employee data, the second is an integer that holds the number of employees contained in the array
//Postcondition: Sorts employees in the structure array by last name

void selectionSort2(File2*, int);
//Precondition: The first parameter is a pointer to a structure array used to hold the employee hours, the second is an integer to hold the number of hours in the array
//Postcondition: Sorts employee hours in the second structure array by employee ID

int binarySearch(File2*, string, int);
//Precondition: The first parameter is a pointer to a structure array used to hold the employee hours, the second is a string that holds the employee ID member from the second struct,the third is an integer that holds the number of hours contained in the array
//Postcondition: Uses a binary search to look through the structure array for employee hours 

void matchHoursWorked(File1*, int, File2*, int);
//Precondition: The first parameter is a pointer to a structure array to hold the employee data, the second is an integer to hold the number of employees in the array, the third is a pointer to a structure array to hold the employee hours, and the fourth is an integer to hold the number of hours in the array
//Postcondition: Matches the hours worked from the second struct to the employees in the first struct using the employee ID

void fileWrite(string, File1*, int);
//Precondition: The first parameter is a string that contains user specified name of the file to write to, the second is a pointer to a structure array to hold the employee data, the third is an integer to hold the number of employees in the array
//Postcondition: Writes the first structure array to a user named file


int main()
{
	string fileName1;
	string fileName2;
	string fileName3;
	int numberOfEmployees = 0;
	int numberOfEmpHours = 0;

	File1 *dataArray1 = nullptr;
	dataArray1 = new File1[numberOfEmployees];

	File2 *dataArray2 = nullptr;
	dataArray2 = new File2[numberOfEmpHours];

	cout << "Enter the name of the file containing the employee data" 
			"(first name, last name, employee number, payrate): " << endl;
	cin >> fileName1;

	numberOfEmployees = getData1(fileName1, dataArray1);

	selectionSort1(dataArray1, numberOfEmployees);

	cout << "Enter the name of the file containing the number of hours worked: " << endl;
	cin >> fileName2;

	numberOfEmpHours = getData2(fileName2, dataArray2);

	selectionSort2(dataArray2, numberOfEmpHours);

	matchHoursWorked(dataArray1, numberOfEmployees, dataArray2, numberOfEmpHours);

	cout << "Enter the name of the file you would like to save the data to: " << endl;
	cin >> fileName3;

	fileWrite(fileName3, dataArray1, numberOfEmployees);

	delete [] dataArray1;
	delete [] dataArray2;

	return 0;
}

int getData1(string fileName1, File1 *dataArray1)
{
	ifstream inputFile;
	int counter = 0;
	float z;
	string w, x, y;

	inputFile.open(fileName1.c_str());

	if (inputFile)
	{
		while (inputFile >> w >> x >> y >> z)
		{
			dataArray1[counter]->firstName = w;
			dataArray1[counter]->lastName = x;
			dataArray1[counter]->employeeNumber = y;
			dataArray1[counter]->payrate = z;
			dataArray1[counter]->hours = 0;
			counter++;
		}
		inputFile.close();
	}

	else
	{
		cout << "There was a problem opening the file->" << endl;
	}

	return counter;
}

int getData2(string fileName2, File2 *dataArray2)
{
	ifstream inputFile;
	int counter = 0,
		z;
	string y;

	inputFile.open(fileName2.c_str());

	if (inputFile)
	{
		while (inputFile >> y >> z)
		{
			dataArray2[counter]->employeeNumber = y;
			dataArray2[counter]->hours = z;
			counter++;
		}
		inputFile.close();
	}

	else
	{
		cout << "There was a problem opening the file->" << endl;
	}

	return counter;
}

void selectionSort1(File1 *dataArray1, int numberOfEmployees)
{
	int startScan, minIndex;
	float minPay;
	string minLast, minFirst, minID;

	for (startScan = 0; startScan < (numberOfEmployees - 1); startScan++)
	{
		minIndex = startScan;
		minLast = dataArray1[startScan]->lastName;
		minFirst = dataArray1[startScan]->firstName;
		minID = dataArray1[startScan]->employeeNumber;
		minPay = dataArray1[startScan]->payrate;

		for (int index = startScan + 1; index < numberOfEmployees; index++)
		{
			if (dataArray1[index]->lastName < minLast)
			{
				minLast = dataArray1[index]->lastName;
				minFirst = dataArray1[index]->firstName;
				minID = dataArray1[index]->employeeNumber;
				minPay = dataArray1[index]->payrate;
				minIndex = index;
			}
		}
		dataArray1[minIndex]->lastName = dataArray1[startScan]->lastName;
		dataArray1[startScan]->lastName = minLast;

		dataArray1[minIndex]->firstName = dataArray1[startScan]->firstName;
		dataArray1[startScan]->firstName = minFirst;

		dataArray1[minIndex]->employeeNumber = dataArray1[startScan]->employeeNumber;
		dataArray1[startScan]->employeeNumber = minID;

		dataArray1[minIndex]->payrate = dataArray1[startScan]->payrate;
		dataArray1[startScan]->payrate = minPay;
	}
}

void selectionSort2(File2 *dataArray2, int numberOfEmpHours)
{
	int startScan, minIndex, minHours;
	string minID;

	for (startScan = 0; startScan < (numberOfEmpHours - 1); startScan++)
	{
		minIndex = startScan;
		minID = dataArray2[startScan]->employeeNumber;
		minHours = dataArray2[startScan]->hours;

		for (int index = startScan + 1; index < numberOfEmpHours; index++)
		{
			if (dataArray2[index]->employeeNumber < minID)
			{
				minID = dataArray2[index]->employeeNumber;
				minHours = dataArray2[index]->hours;
				minIndex = index;
			}
		}
		dataArray2[minIndex]->employeeNumber = dataArray2[startScan]->employeeNumber;
		dataArray2[startScan]->employeeNumber = minID;

		dataArray2[minIndex]->hours = dataArray2[startScan]->hours;
		dataArray2[startScan]->hours = minHours;
	}
}

void matchHoursWorked(File1 *dataArray1, int numberOfEmployees,
	File2 *dataArray2, int numberOfEmpHours)
{
	for (int i = 0; i < numberOfEmployees; i++)
	{
		int j = binarySearch(dataArray2, dataArray1[i]->employeeNumber, numberOfEmpHours);

		if (j >= 0)
		{
			dataArray1[i]->hours = dataArray2[j]->hours;
		}
	}
}

[GG96]

Rest of program.

int binarySearch(File2 *dataArray2, string employeeNumber, int numberOfEmpHours)
{
	int first = 0,
		last = numberOfEmpHours - 1,
		middle,
		position = -1;
	bool found = false;

	while (!found && first <= last)
	{
		middle = (first + last) / 2;

		if (dataArray2[middle]->employeeNumber == employeeNumber)
		{
			found = true;
			position = middle;
		}

		else if (dataArray2[middle]->employeeNumber > employeeNumber)
		{
			last = middle - 1;
		}

		else
		{
			first = middle + 1;
		}
	}
	return position;
}

void fileWrite(string fileName3, File1 *dataArray1, int numberOfEmployees)
{
	ofstream outputFile;
	int counter = 0;

	outputFile.open(fileName3.c_str());

	if (outputFile)
	{
		for (counter; counter < numberOfEmployees; counter++)
		{
			if (dataArray1[counter]->hours > 0)
			{
				float grossPay = dataArray1[counter]->hours * dataArray1[counter]->payrate;

				outputFile << setw(15) << dataArray1[counter]->firstName << setw(15) << dataArray1[counter]->lastName << setw(15)
					<< dataArray1[counter]->employeeNumber << setw(15) << dataArray1[counter]->payrate << setw(15)
					<< dataArray1[counter]->hours << setw(15) << "$" << setprecision(5) << grossPay << endl;
			}
		}
		outputFile.close();
	}

	else
	{
		cout << "There was a problem opening the file." << endl;
	}

}

[AbstractionAnon]

First post:
Line 62: How many instances of File1 do you think are allocated when numberOfEmployees is zero (line 58)?

Line 65: How many instances of File2 do you think are allocated when numberofEmphours is zero (line 59)?

Lines 108-112: Guaranteed to cause an out of bounds reference since no instances were allocated.

Line 130-140: Ditto

[GG96]

Ok if I understand you correctly I didn't actually have any memory allocated because I made it before my counters (numberOfEmployees and numberOfEmphours) had any values. I moved lines 62 and 65 to lines 72 and 79 respectively. However, I still have the expression must have a pointer type error. I tried changing "dataArray[?]->member" to (*(dataArray+?)).member, which I thought were supposed to be the same thing, and it no longer gives me an error. However, when I run the program and open my first file I get an "exception thrown: memory read error" (or something like that). Can you help show me what else I'm doing wrong? Thank you.

[AbstractionAnon]

I didn't actually have any memory allocated because I made it before my counters (numberOfEmployees and numberOfEmphours) had any values.

That's correct.

However, I still have the expression must have a pointer type error.

Your subscript dereferences File * dataarray, so you're referencing a specific element. Use the . (dot) operator.

while (inputFile >> w >> x >> y >> z)
		{
			dataArray1[counter].firstName = w;
			dataArray1[counter].lastName = x;
			dataArray1[counter].employeeNumber = y;
			dataArray1[counter].payrate = z;
			dataArray1[counter].hours = 0;
			counter++;
		}

[GG96]

I tried using the dot operator, but when I ran the program it gave me the same "exception thrown: read access error" after opening the first file like when I used (*(dataArray+?)).member
What else am I doing wrong?