please help me

**hopeolicious** · 02-09-2005

This is the code that is suppose to compute the class's average and standard diviation from a file which contains a collection of student ids and corresponding scores from my computer class and assign each student a letter grade. the class can have no less than 7 students and no more than 25 student

I need help with aeraging the grades

Code:

#include <fstream.h>
#include <iostream.h>
#include <stdlib.h>
#include <iomanip.h>

struct mike
{
int id;
float average = 0;
char lettergrade[1];
int numgrade;
int total = 0;
}hope;

void main()
{
ifstream MyData;
MyData.open("getdata.dat");
ofstream PutData;
PutData.open("putdata");

if(MyData.fail())
 {
        cout << "\n\nFile not successfully opened\n\n";
 }
cout << "\n\nFile Successfully opened\n\n";

int i=0;

do{
MyData >> hope.id >> hope.numgrade;

cout << hope.id << "\t" << hope.numgrade << "\t" << hope.lettergrade << "\t" << hope.average;

hope.total = hope.total + hope.numgrade;
hope.average = hope.average/hope.total;

if (hope.numgrade >= 90) strcpy(hope.lettergrade,"A");
else if (hope.numgrade >= 80) strcpy(hope.lettergrade,"B");
else if (hope.numgrade >= 70) strcpy(hope.lettergrade,"C");
else if (hope.numgrade >= 60) strcpy(hope.lettergrade,"D");
else strcpy(hope.lettergrade,"F");


PutData << "\n\n\n    Class Grades";
PutData << "\n";
PutData << "               Student ID: " << hope.id << endl;
PutData << "      Student Numbergrade: " << hope.numgrade << endl;
PutData << "      Student Lettergrade: " << hope.lettergrade << endl;
PutData << setiosflags(ios::fixed)
        << setiosflags(ios::showpoint)
        << setprecision(2);
PutData << "            Class Average: " << hope.average << endl;
}while(i>7 && i<25);

MyData.close();
PutData.close();
}

**RoD** · 02-09-2005

First, this title does not meet the standards of our forums. Secondly, do a board search as this has been covered. At the very least be more specific as to where your problem is...

**hopeolicious** · 02-10-2005

Can Someone help me in finding the average when I compile my average stays at 0.00

Code:

// Project: This project is designed to compute class's average
// and standard deviation from a file which contains a collection
// of students' ids and corresponding scores for my computer class
// Then it will assign each student a lettergrade as follows:
//  100-90 = A, 89-80 = B, 79-70 = C, 69-60 = D, BELOW 60 = F

#include <fstream.h>
#include <iostream.h>
#include <stdlib.h>
#include <iomanip.h>


struct mike
{ // declaring variables
int id;
float average;
char lettergrade[1];
int numgrade;
}hope;

// DEFINING MAIN FUNCTION
void main()
{
ifstream MyData;
MyData.open("getdata.dat");
ofstream PutData;
PutData.open("putdata");

if(MyData.fail())
 {
        cout << "\n\nFile not successfully opened\n\n";
 }
cout << "\n\nFile Successfully opened\n\n";

int i;

do{
i++;
MyData >> hope.id >> hope.numgrade;
hope.average = hope.numgrade/i;

PutData << "\n\n" << hope.id << "\t" << hope.numgrade << "\t" << hope.lettergrad
e << "\t" << hope.average << endl;
cout << "\n\n" << hope.id << "\t" << hope.numgrade << "\t" << hope.lettergrade <
< "\t" << hope.average << endl;

if (hope.numgrade >= 90)
strcpy(hope.lettergrade,"A");
else if (hope.numgrade >= 80) strcpy(hope.lettergrade,"B");
else if (hope.numgrade >= 70) strcpy(hope.lettergrade,"C");
else if (hope.numgrade >= 60) strcpy(hope.lettergrade,"D");
else strcpy(hope.lettergrade,"F");

PutData << "\n    Class Grades";
PutData << "\n";
PutData << "               Student ID: " << hope.id << endl;
PutData << "      Student Numbergrade: " << hope.numgrade << endl;
PutData << "      Student Lettergrade: " << hope.lettergrade << endl;
PutData << setiosflags(ios::fixed)
        << setiosflags(ios::showpoint)
        << setprecision(2);
PutData << "            Class Average: " << hope.average << endl;


cout << "\n    Class Grades";
cout << "\n";
cout << "               Student ID: " << hope.id << endl;
cout << "      Student Numbergrade: " << hope.numgrade << endl;
cout << "      Student Lettergrade: " << hope.lettergrade << endl;
cout << setiosflags(ios::fixed)
        << setiosflags(ios::showpoint)
        << setprecision(2);
cout << "     Class average is " << hope.average << endl;
cin.get();
}while(i<25);

MyData.close();
PutData.close();

**Hunter2** · 02-10-2005

>>int i;
i isn't initialized. It'll probably start out at about 2,000,000,000.

>>hope.average = hope.numgrade/i;
I have no idea what you're trying to do here. What is numgrade? What is i supposed to represent? How is the data laid out in the file? You'll have to provide a lot more information.

**AH_Tze** · 02-10-2005

I'm getting this error in dev-c++:

9 C:\Dev-Cpp\projects\main.cpp ISO C++ forbids initialization of member `average'

Need to look up, but it seems reasonable that you can't assign a default value like that (outside of making it static, which is not what you want.

That's a benefit of classes, the constructor can take care of stuff like that.

Code:

struct hope  // you're not hacking c anymore
{
int id;
float average = 0;     // apparently not legal
char lettergrade[1];
int numgrade;
int total = 0;
};

**Hunter2** · 02-10-2005

Indeed, you cannot initialize values like that. There is no need in C since classes do not exist and you can initialize variables manually after creation, but in C++ a mechanism has been provided for initializing members of structs/classes: Constructors.

Code:

struct hope
{
int id;
float average;
char lettergrade[1];
int numgrade;
int total;

hope() :average(0.f), total(0) {}  //Initialize average and total to 0 on creation
};

**AH_Tze** · 02-10-2005

hmm... interesting. Trying to make this work, but getting a syntax error I don't understand.

Code:

#include <fstream>
#include <iostream>
#include <cstdlib>
#include <iomanip>
using namespace std;

class hope
{
      public:
    int id;
    float average;
    char lettergrade[1];
    int numgrade;
    int total;
    
    hope() {average = 0; total = 0;};
};

int main()
{
ifstream MyData;
MyData.open("getdata.dat");
ofstream PutData;
PutData.open("putdata");

if(MyData.fail())
 {
        cout << "\n\nFile not successfully opened\n\n";
 }
else
{
    cout << "\n\nFile Successfully opened\n\n";
    
    int i=0;
    
    do{
    MyData >> hope.id >> hope.numgrade; // syntax error here
    
    cout << hope.id << "\t" << hope.numgrade << "\t" << hope.lettergrade << "\t" << hope.average;
    
    hope.total = hope.total + hope.numgrade;
    hope.average = hope.average/hope.total;
    
    if (hope.numgrade >= 90) strcpy(hope.lettergrade,"A");
    else if (hope.numgrade >= 80) strcpy(hope.lettergrade,"B");
    else if (hope.numgrade >= 70) strcpy(hope.lettergrade,"C");
    else if (hope.numgrade >= 60) strcpy(hope.lettergrade,"D");
    else strcpy(hope.lettergrade,"F");
    
    
    PutData << "\n\n\n    Class Grades";
    PutData << "\n";
    PutData << "               Student ID: " << hope.id << endl;
    PutData << "      Student Numbergrade: " << hope.numgrade << endl;
    PutData << "      Student Lettergrade: " << hope.lettergrade << endl;
    PutData << setiosflags(ios::fixed)
            << setiosflags(ios::showpoint)
            << setprecision(2);
    PutData << "            Class Average: " << hope.average << endl;
    }while(i>7 && i<25);
}

MyData.close();
PutData.close();
}

**Hunter2** · 02-10-2005

I'm assuming you're getting an error that tells you that hope isn't an object. Well, that's because hope is the class/struct type, and you haven't declared an instance of hope anywhere. In the original code, the struct type was mike and an object called hope was created immediately.

**AH_Tze** · 02-10-2005

oh man....
/smacks head.

I'm going to sheepishly blame that on the naming scheme and the fact I was thinking about C.

then this might work:

Code:

#include <fstream>
#include <iostream>
#include <cstdlib>
#include <iomanip>
using namespace std;

struct mike
{
    int id;
    float average;
    char lettergrade[1];
    int numgrade;
    int total;
    
    mike() : average(0.f), total(0) {};  // initialize members
} hope;

int main()      // int: not just a good idea, it's the law
{
ifstream MyData;
MyData.open("getdata.dat");
ofstream PutData;
PutData.open("putdata");

if(MyData.fail())
 {
        cout << "\n\nFile not successfully opened\n\n";
 }
else              // do following if data stream opened
{
    cout << "\n\nFile Successfully opened\n\n";
    
    int i=0;
    
    do{
    MyData >> hope.id >> hope.numgrade;
    
    cout << hope.id << "\t" << hope.numgrade << "\t" << hope.lettergrade << "\t" << hope.average;
    
    hope.total = hope.total + hope.numgrade;
    hope.average = hope.average/hope.total;   // apparently suspicious
    
    if (hope.numgrade >= 90)
    strcpy(hope.lettergrade,"A");
    else if (hope.numgrade >= 80) strcpy(hope.lettergrade,"B");
    else if (hope.numgrade >= 70) strcpy(hope.lettergrade,"C");
    else if (hope.numgrade >= 60) strcpy(hope.lettergrade,"D");
    else strcpy(hope.lettergrade,"F");
    
    
    PutData << "\n\n\n    Class Grades";
    PutData << "\n";
    PutData << "               Student ID: " << hope.id << endl;
    PutData << "      Student Numbergrade: " << hope.numgrade << endl;
    PutData << "      Student Lettergrade: " << hope.lettergrade << endl;
    PutData << setiosflags(ios::fixed)
            << setiosflags(ios::showpoint)
            << setprecision(2);
    PutData << "            Class Average: " << hope.average << endl;
    }while(i>7 && i<25);
}

MyData.close();
PutData.close();
}

**Scribbler** · 02-10-2005

The problem is probably that numgrade and the counter i are both integers. Eventually your counter probably gets higher than one of the grade scores, resulting in 0. ie.. 5 / 6 == 0 in integer math.

Additionally, staring at your code, I'm not entirely certain what you are trying to accomplish with

Code:

hope.average = hope.numgrade/i;

It appears as if you're averaving each grade as it comes through.

**7stud** · 02-10-2005

For these lines:

strcpy(hope.lettergrade,"A");

You can do this instead:

hope.lettergrade[0]='A';

...but if you use cout to display the lettergrade you also have to use array notation as well. You can't output the contents of a char array using just the name unless there is a '\0' in the last position of the array. So, you would do this:

cout<<hope.lettergrade[0];

**AH_Tze** · 02-10-2005

Post a valid data file so we can test it.

I don't know about everyone else here, but I have trouble finding bugs by just staring at code and being extremely clever.

And building off what 7stud said, if the grade string is just 1 character long, you could just use a char instead of an array of char's.
If you want to support multiple characters, the STL string is always preferred.

**7stud** · 02-10-2005

The problem is probably that numgrade and the counter i are both integers. Eventually your counter probably gets higher than one of the grade scores

I don't see how that's possible since the scores are going to be 30, 50, 70, 90, etc., so a running total of scores should always be greater than the number of students. But, since the poster made the total a float, it seems they want a float for the total, so they should just make all the values floats.

The average only needs to be calculated after the loop, and I would think all the output would be outside the loop as well, but maybe they are doing it that way for error checking at this point.

Code:

int i = 0;

do{
MyData >> hope.id >> hope.numgrade;
i++;
hope.total = hope.total + hope.numgrade;
hope.average = hope.total/i;

**Scribbler** · 02-10-2005

Dunno, I'm guessing he might have a really low score in there somewhere. If one of the last scores is < 20 it could happen. Who knows, maybe he gave somebody a single digit grade. I remember a lot of old class projects similar to this one, I'd just enter a bunch of random junk data (until I learned that a controlled environment was better for debugging).

It's a logic error. Whether it's the cause in this case remains to be seen.

**7stud** · 02-10-2005

Originally Posted by Scribbler

Dunno, I'm guessing he might have a really low score in there somewhere. If one of the last scores is < 20 it could happen.

Code:

90 70 60 50 10 --> total = 280

1  2  3  4  5  --> i = 5       average = 280/5 = 56

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