Thread: Multiple-Choice Exam Program

I have to write a multiple choice program and the following code is as far as i've gotten. It's coming back with a value of 0


You’ve been asked to write a program to grade a multiple choice exam. The exam has 20 questions, each answered with a little in the range of ‘a’ through ‘f’. The data are stored on a file(exams.dat) where the first line is the key consisting of a string of 20 characters. The remaining lines on the files are exam answers, and consist of a student ID number, a space, and a string of 20 characters. The program should read the key, then read each exam and output the ID number and score to file scores.dat. Erroneous input should result in an error message. For example, given the data:

abcdefabcdefabcdefab
1234567 abcdefabcdefabcdefab
9876543 abddefbbbdefcbcdefac
5554446 abcdefabcdefabcdef
4445556 abcdefabcdefabcdefabcd
3332221 abcdefghijklmnopqrst

The program should output on scores.dat:

1234567 20
9876543 15
5554446 Too few answers
4445556 Too many answers
3332221 Invalid answers

Use functional decomposition to solve the problem and code the solution using functions as appropriate. Be sure to use proper formatting and appropriate comments in your code. The output should be neatly formatted, and the error messages should be informative.

Code:

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

using namespace std;

void WrongSize (ofstream&, int, string, string);

int main()
{
ifstream inData;
ofstream outData;
inData.open("exam.dat");
outData.open("scores.dat");

string key;
string student;
string answers;
int keylength;

inData >> key;
keylength = key.length();

do
{
inData >> student;
outData << student<< " ";
inData >> answers;
WrongSize (outData, keylength, answers, key);

}
while (!inData.eof());

return 0;
}


void WrongSize (ofstream& outData, int keylength, string answers, string key)
{

int grade = 0;
if (answers.length() < keylength)
{
outData << "Too few answers";
}
else if (answers.length() > keylength )
{
outData << "Too many answers";
}
else
{
bool check=false;

for (int count = 0; count < key.length(); count++)
{
if( answers[count] == key[count] )
grade++;
else if (answers[count] != 'a' && answers[count] != 'b' && answers[count] != 'c' && answers[count] != 'd' && answers[count] != 'e' && answers[count] != 'f')
check=true;
}

if (check==true)
{
outData << "Invalid Answer";
}
else
{
outData << grade;
}
}
outData << endl;
}

Your program should return 0, since that indicates successful completion of the program (as evidenced by "return 0" in your code). The real question is, what's in your output file.

The output file simply reads "0". That's what the problem is...

Your code says one thing ("exam.dat") while your description says another ("exams.dat").

Of course it has to be something very simple like that lol. Thanks so much.

My only problem I have left is the output says:

1234567 20
9876543 15
5554446 Too few answers
4445556 Too many answers
3332221 Invalid Answer
3332221 Invalid Answer

That last line shouldn't be repeating itself. Thoughts?

Originally Posted by micmagicfly

That last line shouldn't be repeating itself. Thoughts?

Don't screw up the eof check? (Remember: eof doesn't happen until after a read has failed; so you need to make sure the read is the last thing that happens before the condition is checked. This is usually done by making the read the actual condition itself, since the read will return true/false for whether it worked or not.)

So do I get rid of the eof function..? I'm not sure what i'd use to replace it.