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Join Date: Jun 2007

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zandiago

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c++ scores

Oct 25th, 2007

Good day. My infile contains the following:

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C++ Syntax (Toggle Plain Text)

TFFTFFTFFTFFTFTFTFTFFF
A33
TFFTFFTFFFFFTFTFTFFFFT
Z27
TFFTFFTFFTFFTFTFTFTFFT
X12
TFTT FTFFTFFFT FTFTFFF
H44
TFFTFFTFFTFFFFTFTFFTFF
Q19
FFFFFFFFFFFFTFTFTFFFFF
D72
TFFTFFTFFTFF FFFFFTFFF
W32
FFFTFFTFFTFFTFTFTFFTTT
Y09
TFFTFFTFFTFFTFFTTFFTTT
S44
TFFTFFTFFTFFTFTFTFTFFF
G11
FFTFFTFFTFFTFTFTTFTFFF
J21
TFFTFFFFFTFFTFTFTFTFTT
K61
TFFTFFTFFTFFTFTFTFTFT 
M03
TFFTFFTFFFFFTFTFTFTFFT
P24
TFFTFFTFFTFFTFTFTFFFFT
N54
FTFFTFFTFT TFF FTFTFFF
F33
TFFTFFTFFTFFTFTFTFTFFF
Z21
TFFTFFFTTFTTFFTFTFTFTF
V39
TFFFTTFTTFTTFTFTFTTFFF
O66
TTFTFFTFFTFFTFTFTFTFFF
B29
TFFTFFTFFTFF FFTTFFTFF
J17
TFFTFFFTTTFFTFFTFTFTTT
K09
TFFTFFTFTTFTTFTFTFFTFF
L99
FFTFFTFFTFFFFTFTFTFFF

My assignment:
The history teacher at the school needs help in grading a True/False test. The
student lD’s and test answers are stored (vertically) in a file named "tftest.txt". The
first entry in the file contains answers to the test in the form
TFFTFFTTTTFFTFTFTFTFTT
All of the other entries in the file are data for a student on 2 lines:
A43
TFFTFFTT TFTFTFFTTFTTT
Note that this student did not answer question 9. The test has 22 questions and
there are not more than 50 students in the class. Each correct answer is awarded 5
points, each incorrect answer is awarded -2 points (negative) and each "no answer"
gets a value of -4 points (negative).
lt can be seen that all test scores will be a whole number.
The student in the example achieved a grade as follows:
14 correct * 5 = 70
7 incorrect * -2 = -14
1 no answer *-4 = -4
70 - 14 -4 = 52 F
His output line would look like:
A43 TFFTFFTT TFTFTFFTTFTTT 52 F
The output should be the student’s ID, the student’s answers followed by the test
score and the test grade. The grade scale is:
Above 90 = A
80 - 89 = B
70 - 79 = C
60 - 69 = D
Below 60 = F
The program should finally display the class average (2 decimals)
...Now where do i even begin? Since the 1st line contains the correct answer...how do i store them so that the other lines are compared to it for the correct answer. I really need a jumpstart with this one. If i use a getline function for example...how will it diffrentiate between the answers i wanna check and the student's id #?
Thanks for all the pointers & input.

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Join Date: Oct 2007

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Ptolemy

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Re: c++ scores

Oct 25th, 2007

>...Now where do i even begin?
You could use everything you've learned in your previous threads that do something similar.

>how do i store them so that the other lines are compared to it for the correct answer.
Just store it in an array:

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 C++ Syntax (Toggle Plain Text) 
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
 
namespace {
  const int NQUESTIONS = 22;
}
 
int main()
{
  std::ifstream in ( "sourcefile" );
 
  if ( !in ) {
    std::cerr<<"File open failure\n";
    return EXIT_FAILURE;
  }
  else {
    char answers[23];
 
    // Get the correct answers
    if ( !in.getline ( answers, sizeof answers )
      || std::strlen ( answers ) != NQUESTIONS )
    {
      std::cerr<<"Invalid file format\n";
      return EXIT_FAILURE;
    }
 
    // Process each subsequent record
  }
 
  return EXIT_SUCCESS;
}
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>

namespace {
  const int NQUESTIONS = 22;
}

int main()
{
  std::ifstream in ( "sourcefile" );

  if ( !in ) {
    std::cerr<<"File open failure\n";
    return EXIT_FAILURE;
  }
  else {
    char answers[23];

    // Get the correct answers
    if ( !in.getline ( answers, sizeof answers )
      || std::strlen ( answers ) != NQUESTIONS )
    {
      std::cerr<<"Invalid file format\n";
      return EXIT_FAILURE;
    }

    // Process each subsequent record
  }

  return EXIT_SUCCESS;
}

>If i use a getline function for example...how will it diffrentiate
>between the answers i wanna check and the student's id #?
Obviously because the ID numbers and scores are on two different lines. You read the ID first, then on the next line start processing scores...

Last edited by Ptolemy; Oct 25th, 2007 at 1:15 pm.

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Join Date: Jul 2005

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Lerner

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Re: c++ scores

Oct 25th, 2007

Each line in the file could be read in as a string. The first string would be stored as the correct answer string. The remaining lines alternate between student ID strings and the student answer strings. Once you have a student answer string you compare each element of that string with each element of the correct answer string and keep track of all the appropriate pieces of information with variables that act as counters.

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Ptolemy

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Re: c++ scores

Oct 25th, 2007

>Once you have a student answer string you compare each element
>of that string with each element of the correct answer string
But from the sample file it looks like if the last N answers were blank, the string is trimmed by that many characters. You also have to keep track of where you hit the end of the student answer string and subtract the correct number of "no answer" values from the score.

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Lerner

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Re: c++ scores

Oct 25th, 2007

>>But from the sample file it looks like if the last N answers were blank, the string is trimmed by that many characters. You also have to keep track of where you hit the end of the student answer string and subtract the correct number of "no answer" values from the score.

True enough. But I like it better than using sequential calls to something like get(), which would read the file one char at a time without ignoring whitespace, which is the alternative I can think of off the top of my head.

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Ptolemy

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Re: c++ scores

Oct 25th, 2007

Oh, don't read it as me bashing your solution, it's the same one I'd use. I was just mentioning that little pitfall because I'd noticed it while brainstorming.

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WaltP

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Re: c++ scores

Oct 25th, 2007

Personally, I'd read the test answers into a char* rather than a C++ string. A char* must be defined to accommodate the total number of answers necessary, but a string will read only the answers on the line. If a student doesn't answer the last 5 questions, the string could be short and cause problems. A char* will still have data, however it will have to be cleared after each use.

The 3 Laws of the Procrastination Society:
1) Never do today that which can be put off until tomorrow
2) Tomorrow never comes

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Lerner

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Re: c++ scores

Oct 25th, 2007

If there's supposed to be 20 answers but the last question is unanswered then I suppose it will depend on whether there is a space before the newline char at the end of the line in the file or whether the newline char is right after the T/F for answer 19. If the newline char is right after the answer for question 19 and the line is then read in as a char *, or say char line[21], I wonder whether there would be a null char at line[19] or a space at line[19]? Guess I'll have to try it out for myself when I get the chance.

Last edited by Lerner; Oct 25th, 2007 at 9:13 pm.

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Lerner

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Re: c++ scores

Oct 25th, 2007

Tested basic code below:

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ofstream fout("practiceText");
char first[6] = "TTTT ";  //"TTTT";
fout << first << endl;
fout.close();
 
ifstream fin("practiceText");
 
char first2[6];
fin.getline(first2, 6);
 
//string first2;
//getline(fin, first2);
 
cout << first2 << endl;
 
if(first2[4] == ' ')
    cout << "space" << endl;
else 
    cout << "no space" << endl;
 
fin.close();
ofstream fout("practiceText");
char first[6] = "TTTT ";  //"TTTT";
fout << first << endl;
fout.close();

ifstream fin("practiceText");

char first2[6];
fin.getline(first2, 6);

//string first2;
//getline(fin, first2);

cout << first2 << endl;

if(first2[4] == ' ')
    cout << "space" << endl;
else 
    cout << "no space" << endl;

fin.close();

Using "TTTT " the version with first2 declared as char[] and string both output space whereas with "TTTT" the version with first2 declared as char[] and string both output no space.

Therefore, if file is set up with trailing spaces as needed for unanswered questions at end of answer line then reading in as either string or char[] should pick up that information whereas if file is set up with newline right after last T/F in the line, then allowances must be made irrespective of type read into. In addition, there's no apparent benefit to reading in answer line char by char with get() instead of with the appropriate version of getline().

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zandiago

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Re: c++ scores

#10

Oct 26th, 2007

Good day:

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 C++ Syntax (Toggle Plain Text) 
#include <iomanip>
#include <cmath>
#include <fstream>
#include<string>
#include<iostream>
 
using namespace std;
 
void initialize(char test, int sstudent[30]);
void getdata(char test, int sstudent[30]);
 
int main()
 
{
 
	ifstream inFile;
	ofstream outFile;
 
	inFile.open ("tftest.txt");
	outFile.open ("testout");
 
	int i, j, k;
    int total=0;
 
    char test;
	int student[30];
    initialize(test,student);
    getdata(test,student);
 
	for(i = 2; i < 30; i = i + 2)
    {
        for(j = 0; j < 22; j++)
        {
             cout << student[0].answer.substr(j,1);              
 
             if(student[0].answer.substr(j,1) == student[i].answer.substr(j,1))
             {
                   total = total + 5;
             }//end if
             else if(student[i].answer.substr(j,1) == " ")
             {
                   total = total - 4;
             }//end else
             else
             {
                   total = total - 2;
             }//end else  
        }//end for
 
 
 
    }//end for
 
    return 0;
}// end of main function
//********************************** Function Definitions
void initialize(test sstudent[30])
{
    int i;
    for(i = 1; i < 30; i++)
    {
        sstudent[i].id = "";
        sstudent[i].answer = "";
 
    }//end for
}//end initialize
//***********************************
void getdata(test sstudent[30])
{
    int i;
 
    getline(infile, sstudent[0].answer);
 
    for(i = 1; i < 30; i++)
    {
        getline(infile, sstudent[i].id);
        getline(infile, sstudent[i].answer);
 
    }//end for
 
    infile.close();
 
}//end getdata
//************************************
#include <iomanip>
#include <cmath>
#include <fstream>
#include<string>
#include<iostream>

using namespace std;

void initialize(char test, int sstudent[30]);
void getdata(char test, int sstudent[30]);

int main()

{
		
	ifstream inFile;
	ofstream outFile;

	inFile.open ("tftest.txt");
	outFile.open ("testout");

	int i, j, k;
    int total=0;
    
    char test;
	int student[30];
    initialize(test,student);
    getdata(test,student);

	for(i = 2; i < 30; i = i + 2)
    {
        for(j = 0; j < 22; j++)
        {
             cout << student[0].answer.substr(j,1);              
             
             if(student[0].answer.substr(j,1) == student[i].answer.substr(j,1))
             {
                   total = total + 5;
             }//end if
             else if(student[i].answer.substr(j,1) == " ")
             {
                   total = total - 4;
             }//end else
             else
             {
                   total = total - 2;
             }//end else  
        }//end for
        
        
            
    }//end for
    
    return 0;
}// end of main function
//********************************** Function Definitions
void initialize(test sstudent[30])
{
    int i;
    for(i = 1; i < 30; i++)
    {
        sstudent[i].id = "";
        sstudent[i].answer = "";
            
    }//end for
}//end initialize
//***********************************
void getdata(test sstudent[30])
{
    int i;
    
    getline(infile, sstudent[0].answer);
    
    for(i = 1; i < 30; i++)
    {
        getline(infile, sstudent[i].id);
        getline(infile, sstudent[i].answer);
        
    }//end for
    
    infile.close();
    
}//end getdata
//************************************

Considering the fact that my profesor requires functions, i thought i'd have it like this. Thx for your input.