Thread: File Input/Output ... Problems

My intention is to test for a data type token in the
studentdata.txt file, either "HWK," "EXM," or "END."
If it is HWK then the next number is added to a homework
score array; if it is EXM, then the next number is added to
an exam score array. After END is parsed, the inside while
loop breaks and finishes the calculations for the particular
student, and then outputs the information in an organized
manner.

The studentdata.txt file is set up like this:

John Doe HWK 67 HWK 43 EXM 88 HWK 76 HWK 49 EXM 95 HWK 28 HWK 64 EXM 80 END
Adam Rest HWK 48 HWK 82 EXM 98 HWK 73 HWK 55 EXM 100 HWK 68 HWK 54 EXM 70 END

Et cetera. 6 homework scores, 3 exam scores. If you need the
actual file, ask.

No values are being added into the homework array because dataType == "HWK" and dataType == "END" are NEVER being true. Although, for testing, I printed out dataType and it printed out as "HWK," so I don't know why it is not working. Also, the while (dataType != "END") is never ending, because it seems as though "END" is never being put into dataType.

I'd be grateful for any help. I'm new at C++, and my teacher isn't
much help because he totally doesn't care, so if there is some
stupid mistake, go easy on me. I'd appreciate any help beyond
the span of human comprehension.

Code:

#include<iostream>
#include<fstream>

using std::cout;
using std::cin;
using std::endl;
using std::ios;
using std::ifstream;
using std::ofstream;

int main() {

	ifstream fin;
	ofstream fout;

	char firstName[30]; //student's first and
	char lastName[30];  //last name
	char dataType[4];	//holds type of following score
	int homework[6] = {0}; //array of student's homework scores
	int exam[4] = {0};     //array of student's exam scores

	float totalAvg = 0;	//Total weighted average
	float examTotal = 0;//Exam scores totaled
	float examAvg = 0;  //Exam average
	float homeworkTotal = 0; //Homework scores totaled
	float homeworkAvg = 0;   //Homework average
	int score = 0;

	int a = 0; //holds homework index
	int	b = 0; //holds exam index

	//Opens the data file
	fin.open("studentdata.txt", ios::in);
	fout.open("studentGrades.txt", ios::out);

	//Tests to see if the input file were opened.
	//If opened correctly, we move on.
	if (!fin) {
		cout << "File could not be opened for input.";
		exit(1);
	}

	//Tests to see if the output file were opened/created.
	//If opened/created correctly, we move on.
	if (!fout) {
		cout << "File could not be opened/created for output.";
		exit(1);
	}

	//Outputs headings to output file.
	fout << "Student Name" << "\t"
		 << "Overall" << "\t"
		 << "Homework Scores:" << "\t"
		 << "Hwk Avg" << "\t"
		 << "Exam Scores:" << "\t"
		 << "Exam Avg" << "\t\n";

	//Continue loop until end of file
	while (!fin.eof()) {

		//Takes student's name
		fin >> firstName
			>> lastName;

		while (dataType != "END") {

		fin >> dataType;

		//Determines where to place score
		if ( dataType  == "HWK" ) 
		{
			fin >> homework[a];
			a++;
		}
		else if ( dataType == "EXM" ) 
		{
			fin >> exam[b];
			b++;
		}
		}

		//Determines homework total
		for (int e = 0; e <= 5; e++) {
			homeworkTotal += homework[e];
		}
		//Determines homework average
		homeworkAvg = homeworkTotal / 6;

		//Determines exam total
		for (int f = 0; f <= 2; f++) {
			examTotal += exam[f];
		}
		//Determines exam average
		examAvg = examAvg / 3;

		//Determines total weighted average
		totalAvg = (examAvg * .6) + (homeworkAvg * .4);



		//Outputs student's name to the output file
		fout << firstName << " "
			 << lastName << "\t";

		//Outputs the student's total weighted average
		fout << totalAvg << "\t";

		//Outputs the student's homework scores
		for (int c = 0; c <= 5; c++) {
			fout << homework[c] << " ";
		}

		//Outputs the student's homework average
		fout << "\t\t" << homeworkAvg << "\t";

		//Outputs the student's exam scores
		for (int d = 0; d <= 2; d++) {
			fout << exam[d] << " ";
		}

		//Outputs the student's exam average
		fout << "\t\t" << examAvg << "\n";

	}



	fin.close();
	fout.close();

	return 0;

}

Code:

		while (dataType != "END") {

		fin >> dataType;

		//Determines where to place score
		if ( dataType  == "HWK" ) 
		{
			fin >> homework[a];
			a++;
		}
		else if ( dataType == "EXM" )

You can compare C++ style strings your way, but not char arrays. Use strcmp() for char arrays:

Code:

#include <cstring>
.
.
.
		while ( strcmp( dataType,"END" ) != 0 ) {

		fin >> dataType;

		//Determines where to place score
		if ( strcmp( dataType, "HWK" ) == 0 ) 
		{
			fin >> homework[a];
			a++;
		}
		else if ( strcmp( dataType,"EXM" ) == 0 )

To elaborate on WHY that fails, remember that arrays and pointers are essentially the same thing, and that a pointer is an ADDRESS.

So, for example, this:
if (dataType == "HWK")

Really means "If the array named datatype begins at the same memory location as the string literal "HWK" begins at..."

And this will never, ever return true, because dataType is allocated on the stack, and "HWK" exists somewhere with other constants and string literals.