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Reading wrong int value from external file

Paul Reed (11)
Here I have code for a homework assignment. I am required to read from two different files.
From the first file, I have to read 10 names.
From the second, 5 grades for each of the 10 names.
I was close to completing the project, but come to find out, when I open "grades.txt", it is reading the wrong value for the 5th integer, and the rest after that are completely off.
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//This program reads 10 names and 5 grades from various files and averages them.

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

using namespace std;  // to prevent having to use std:: every time we use certain functions

	int main()   // main function
	{
		ifstream nam, grd;
		ofstream aver;             // this will be the output file's stream
		int grd1, grd2, grd3, grd4, grd5;  //Holds the sums of the 5 grades
		string nam1, nam2, nam3, nam4, nam5, nam6, nam7, nam8, nam9, nam10; //These are variables that hold the name strings
		int grade [9] [4];  // I decided to try and use an array to hold the grade values

		cout<< "Welcome to the grade averager.\n";

		nam.open("C:\\Users\\Alex\\Desktop\\names.txt");
		cout <<"Opening names.txt\n";
		if (!nam)
		{
			cout << "Error Opening File. Sorry...\n";
			return 0;
		}

		nam >> nam1 >> nam2>> nam3 >> nam4 >> nam5
			>> nam6 >> nam7 >> nam8 >> nam9 >> nam10;       // Assigns the names in the file "names.txt" to a variable accesible in
		                                                    // the program.
		nam.close();
			cout << "The names have been loaded. \n";       // close the stream
			cout << "Press ENTER to continue..\n";
			cin.get();
			
		grd.open("C:\\Users\\Alex\\Desktop\\grades.txt");   // Open the file with the sets of grades in them

		cout << "Attemtping to open grades.txt\n";
		if(!grd)
		{
			cout << "Was unable to locate ""grades.txt""\n"; // makes sure that grades.txt was successfully opened.
			return 0;
		}

		grd >> grade [0] [0] >> grade [0] [1] >> grade [0] [2] >> grade [0] [3] >> grade [0] [4]
		>> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
		>> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
		>> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
		>> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4];    //load all the grades from the file. I read that
		                                                                                       //you are only allowed to assign one array at a time.
		                                                                                       // I am unsure if there is a faster way of doing this
		grd1= ((grade [0] [0] + grade [0] [1] + grade [0] [2] + grade [0] [3] + grade [0] [4])/5);  //Adds then divides, assigns to grd1
		cout << nam1<< "'s grade is ["<< grd1<<  "]" << endl;

		grd2= (( grade [1] [0] + grade [1] [1] + grade [1] [2] + grade [1] [3]+ grade [1] [4])/5);
		cout << nam2<< "'s grade is ["<< grd2<<  "]" << endl;
		
		grd3= (( grade [2] [0] + grade [2] [1] + grade [2] [2] + grade [2] [3]+ grade [2] [4])/5);
		cout << nam3<< "'s grade is ["<< grd3<<  "]" << endl;

		grd4= (( grade [3] [0] + grade [3] [1] + grade [3] [2] + grade [3] [3]+ grade [3] [4])/5);
		cout << nam4<< "'s grade is ["<< grd4<<  "]" << endl;

		grd5= (( grade [4] [0] + grade [4] [1] + grade [4] [2] + grade [4] [3]+ grade [4] [4])/5);
		cout << nam5<< "'s grade is ["<< grd5<<  "]" << endl;

		cout<< grade [0] [4];

		cout << "Press ENTER to end.";
		cin.get();
		return 0;
	}
Last edited on
Paul Reed (11)
Ok, with the help of xcode, i found that on line 15, int [9] [4] is wrong, and was cleared up by changing the 4 to a 5. I am unsure as to why this is, since an array initialized to 4 would hold 5 values..
vlad from moscow (6539)
You declared the array as

int grade [9] [4];

So the indexes of the second dimension can be in the range 0 - 3 but you are trying access elements with the second index equal to 4.

grd >> grade [0] [0] >> grade [0] [1] >> grade [0] [2] >> grade [0] [3] >> grade [0] [4] >> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
>> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
 >> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
>> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4];


Also you are filling only two rows of the array: 0 and 1 but in the code you are using rows 2 - 4.

grd3= (( grade [2] [0] + grade [2] [1] + grade [2] [2] + grade [2] [3]+ grade [2] [4])/5);
cout << nam3<< "'s grade is ["<< grd3<< "]" << endl;

grd4= (( grade [3] [0] + grade [3] [1] + grade [3] [2] + grade [3] [3]+ grade [3] [4])/5);
cout << nam4<< "'s grade is ["<< grd4<< "]" << endl;

grd5= (( grade [4] [0] + grade [4] [1] + grade [4] [2] + grade [4] [3]+ grade [4] [4])/5);
cout << nam5<< "'s grade is ["<< grd5<< "]" << endl;


Paul Reed (11)
Thanks, i fixed the array input rows already, and I now see my mistake. I knew it started at 0, but i figured since it starts at 0, then initializing to 4 would give me 5 values to input. Thanks Vlad.
Paul Reed (11)
delete
Last edited on
vlad from moscow (6539)
Show your updated program.
Paul Reed (11)
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//
//  main.cpp
//  averages
//
//  Created by Paul Reed on 1/22/13.
//  Copyright (c) 2013 Paul Reed. All rights reserved.
//

//This program reads 10 names and 5 grades from various files and averages them.

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

using namespace std;  // to prevent having to use std:: every time we use certain functions

int main()   // main function
{
    ifstream nam, grd;
    ofstream aver;             // this will be the output file's stream
    int Grade [10];  //Holds the sums of the 5 grades
    string nam1, nam2, nam3, nam4, nam5, nam6, nam7, nam8, nam9, nam10, nam11; //These are variables that hold the name strings
    int grade [9] [5];  // I decided to try and use an array to hold the grade values
    
    cout<< "Welcome to the grade averager.\n";
    
    nam.open("/Volumes/BOOTCAMP/Users/Alex/Desktop/names.txt");
    cout <<"Opening names.txt\n";
    if (!nam)
    {
        cout << "Error Opening File. Sorry...\n";
        return 0;
    }
    
    nam >> nam1 >> nam2>> nam3 >> nam4 >> nam5
    >> nam6 >> nam7 >> nam8 >> nam9 >> nam10>>nam11;
    
    // Assigns the names in the file "names.txt" to a variable accesible inq
    // the program.
    nam.close();
    cout << "The names have been loaded. \n";       // close the stream
    cout << "Press ENTER to continue..\n";
    cin.get();
    
    grd.open("/Volumes/BOOTCAMP/Users/Alex/Desktop/grades.txt");   // Open the file with the sets of grades in them
    
    cout << "Attemtping to open grades.txt\n";
    if(!grd)
    {
        cout << "Was unable to locate ""grades.txt""\n"; // makes sure that grades.txt was successfully opened.
        return 0;
    }
    
    grd >> grade [0] [0] >> grade [0] [1] >> grade [0] [2] >> grade [0] [3] >> grade [0] [4]
    >> grade [1] [0] >> grade [1] [1] >> grade [1] [2] >> grade [1] [3]>> grade [1] [4]
    >> grade [2] [0] >> grade [2] [1] >> grade [2] [2] >> grade [2] [3]>> grade [2] [4]
    >> grade [3] [0] >> grade [3] [1] >> grade [3] [2] >> grade [3] [3]>> grade [3] [4]
    >> grade [4] [0] >> grade [4] [1] >> grade [4] [2] >> grade [4] [3]>> grade [4] [4]
    >> grade [5] [0] >> grade [5] [1] >> grade [5] [2] >> grade [5] [3]>> grade [5] [4]
    >> grade [6] [0] >> grade [6] [1] >> grade [6] [2] >> grade [6] [3]>> grade [6] [4]
    >> grade [7] [0] >> grade [7] [1] >> grade [7] [2] >> grade [7] [3]>> grade [7] [4]
    >> grade [8] [0] >> grade [8] [1] >> grade [8] [2] >> grade [8] [3]>> grade [8] [4]
    >> grade [9] [0] >> grade [9] [1] >> grade [9] [2] >> grade [9] [3]>> grade [9] [4]
    >> grade [10] [0] >> grade [10] [1] >> grade [10] [2] >> grade [10] [3]>> grade [10] [4];

    
    //load all the grades from the file. I read that
    //you are only allowed to assign one array at a time.
    // I am unsure if there is a faster way of doing this
    
    
    
    aver.open("//Users/AlexMac/Desktop/graded.txt", ios::out); //Prepare for file output
    if (!aver)
    {
        cout<< "cannot create file\n.";
        exit(1);
    }

     Grade [0]= ((grade [0] [0] + grade [0] [1] + grade [0] [2] + grade [0] [3] + grade [0] [4])/5);  //Adds                                 then divides, assigns to Grade array [1]
    cout << nam1<< "'s grade is ["<< Grade [0]<<  "]" << endl;
    aver << nam1<< "'s grade is ["<< Grade [0]<<  "]" << endl;
    
    Grade[1]= (( grade [1] [0] + grade [1] [1] + grade [1] [2] + grade [1] [3]+ grade [1] [4])/5);
    cout << nam2<< "'s grade is ["<< Grade[1]<<  "]" << endl;
    aver << nam2<< "'s grade is ["<< Grade[1]<<  "]" << endl;
    
    Grade[2]= (( grade [2] [0] + grade [2] [1] + grade [2] [2] + grade [2] [3]+ grade [2] [4])/5);
    cout << nam3<< "'s grade is ["<< Grade[2]<<  "]" << endl;
    aver << nam3<< "'s grade is ["<< Grade[2]<<  "]" << endl;
    
    Grade[3]= (( grade [3] [0] + grade [3] [1] + grade [3] [2] + grade [3] [3]+ grade [3] [4])/5);
    cout << nam4<< "'s grade is ["<< Grade[3]<<  "]" << endl;
    aver << nam4<< "'s grade is ["<< Grade[3]<<  "]" << endl;

    
    Grade[4]= (( grade [4] [0] + grade [4] [1] + grade [4] [2] + grade [4] [3]+ grade [4] [4])/5);
    cout << nam5<< "'s grade is ["<< Grade[4]<<  "]" << endl;
    aver << nam5<< "'s grade is ["<< Grade[4]<<  "]" << endl;

    
    Grade[5]= (( grade [5] [0] + grade [5] [1] + grade [5] [2] + grade [5] [3]+ grade [5] [4])/5);
    cout << nam6<< "'s grade is ["<< Grade[5]<<  "]" << endl;
    aver << nam6<< "'s grade is ["<< Grade[5]<<  "]" << endl;

    
    Grade[6]= (( grade [6] [0] + grade [6] [1] + grade [6] [2] + grade [6] [3]+ grade [6] [4])/5);
    cout << nam7<< "'s grade is ["<< Grade[6]<<  "]" << endl;
    aver << nam7<< "'s grade is ["<< Grade[6]<<  "]" << endl;

    
    Grade[7]= (( grade [7] [0] + grade [7] [1] + grade [7] [2] + grade [7] [3]+ grade [7] [4])/5);
    cout << nam8<< "'s grade is ["<< Grade[7]<<  "]" << endl;
    aver << nam8<< "'s grade is ["<< Grade[7]<<  "]" << endl;


    Grade[8]= (( grade [8] [0] + grade [8] [1] + grade [8] [2] + grade [8] [3]+ grade [8] [4])/5);
    cout << nam9<< "'s grade is ["<< Grade[8]<<  "]" << endl;
    aver << nam9<< "'s grade is ["<< Grade[8]<<  "]" << endl;


    Grade[9]= (( grade [9] [0] + grade [9] [1] + grade [9] [2] + grade [9] [3]+ grade [9] [4])/5);
    cout << nam10<< "'s grade is ["<< Grade[9]<<  "]" << endl;
    aver << nam10<< "'s grade is ["<< Grade[9]<<  "]" << endl;

    
    aver.close();
    nam.close();
    grd.close();
    
    cout << "Press ENTER to end.";
    cin.get();
    return 0;
}



All done!

Please advise me on anything that could have been done more efficiently.
Last edited on
cire (8284)
int grade [9] [5]; // I decided to try and use an array to hold the grade values 

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    >> grade [9] [0] >> grade [9] [1] >> grade [9] [2] >> grade [9] [3]>> grade [9] [4]
    >> grade [10] [0] >> grade [10] [1] >> grade [10] [2] >> grade [10] [3]>> grade [10] [4];


The first dimension of grade is 9. Which means valid indices for the first dimension of the array are 0-8.
Last edited on
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