Question

Let’s consider a file with the following student information:

John Smith 99
Sarah Johnson 100
Jim Robinson 70
Mary Anderson 95
Michael Jackson 92

Each line in the file contains the first name, last name, and test score of a student.

Write a program that prompts the user for the file name, then calculates and displays the average score by reading the data from the file.

Answer 1

what language? what part can't you do?

Answer 2

c++

Answer 3

and just finding the average part, would you like to see what i have so far?

Answer 4

Yes. We're supposed to assist people, not do their work for them. Post your code and a specific question.

Answer 5

my question would be how to find the average

Answer 6

because the result i get is not the correct one

Answer 7

@rsmith6559

Answer 8

also i am not sure if i should have assigned 0 to totalSum

Answer 9

#include<iostream>
#include<string>
#include<fstream>
using namespace std;

int main()
{
ifstream ins;
string firstName;
string lastName;
string student;
int score;
int totalSum=0;
float average;

cout << "Enter file name: ";
cin >> student;
ins.open(student.c_str());

while (!ins.eof())
{

ins >> firstName >> lastName >> score;
totalSum = totalSum + score;

}

average = totalSum / 5;

cout<<average<<" is the average score.";

ins.close();

system("pause");
return 0;

}

Answer 10

average = totalSum / 5; //assumes that there is alway 5 records read

IMO, your while loop should count the number of records read, and then that value is what totalSum should be divided by.

Just because I think Windows is a toy, you should close your file as soon as you're done with it. Windows has exclusive file locking, only one program can use (even just read) a file at a time. Not a desireable thing on a server.

Answer 11

okay, so you do think my while loop is structured correctly right, do you think there would be room for error?

Answer 12

okay i closed the file, it did nothing

Answer 13

the program is only reading the first line .-.

Answer 14

how do I get my while loop to count the number of records , and then divide totalSum?

Answer 15

nvm i got it

Answer 16

I had to add a variable x and assign it to 0 and then update it in the while loop and then have totalSum/x

Answer 17

The timing of closing the files is just to get you into good habits. As far as the program reading the first line, open your data file and make sure that there's more than one line in the file.

Answer 18

FWIW, double check your results. I wrote a test program of your code and I had to use an if( ins.eof() )
break;
to get the correct answer.

Answer 19

what was the answer you got?

Answer 20

@rsmith6559

Answer 21

this is my updated code

Answer 22

#include<iostream>
#include<string>
#include<fstream>
using namespace std;

int main()
{
ifstream ins;
string firstName;
string lastName;
string student;
int score;
int totalSum=0,x = 0;
float average;

cout << "Enter file name: ";
cin >> student;
ins.open(student.c_str());

while (!ins.eof())
{

ins >> firstName >> lastName >> score;
totalSum = totalSum+score;
x++;
}
ins.close();

average = totalSum / x;

cout<<average<<" is the average score."<<endl;


system("pause");
return 0;

}

Answer 23

and the answer it gives back is 91 of type int

Answer 24

I made it type int b/c when i made it a float it gave me 91.3333... which is not the answer i calculated manually, which was 91.222..

Answer 25

I found out, with the help of cplusplus.com, that my program was processing the last line of the file twice. It would cause just that sort of discrepency. I don't understand why, I'm wondering if the cin is previewing the eof and unsetting the eof bit so that the while statement evaluates to true again.

// Interesting way to HAVE to handle a read loop
while( 1 )
{
inFile >> firstName >> lastName >> score;
if( inFile.eof() )
break;
cout << firstName << " " << lastName << "\t" << score << endl;

Answer 26

okay this is what I updated it to, and it gave me the correct average

Answer 27

#include<iostream>
#include<string>
#include<fstream>
using namespace std;

int main()
{
ifstream ins;
string firstName;
string lastName;
string student;
int score;
int totalSum=0;
float average, x = 0;

cout << "Enter file name: ";
cin >> student;
ins.open(student.c_str());

while (!ins.eof())
{

ins >> firstName >> lastName >> score;

if (ins.eof(), x < 5)
{
totalSum = totalSum + score;
x++;
}
}
ins.close();

average = totalSum / x;

cout<<average<<" is the average score."<<endl;


system("pause");
return 0;

}

Answer 28

@rsmith6559

Answer 29

Just one of those little stinkers that make programming so much fun!