SOMEBODY PLEASE HELP!

[ayanda83]

This program is suppose to calculate the median from a file containing 14 integers separated by spaces. The program doesn't work, it output a negative number as a median. please help.

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

void read_file(ifstream& fin1, int& count11);
//reads the file and calculates the location of the median.

void calc_median(ifstream& fin2, int& count);
//Calculates the median and displays it.

int main()
{
    ifstream in_stream;
    int number, count1 = 0;
    double median;
    
    read_file(in_stream, count1);
    calc_median(in_stream, count1);
    
    in_stream.close();
    
    cout << endl <<endl;
    
    system("PAUSE");
    
    return 0;
}
 
void read_file(ifstream& fin1, int& count11)
{
     int num = 0;
     count11 =0;
         
     fin1.open("myMedian.txt");
     if(fin1.fail())
     {
        cout << "Input file failed to open" <<endl;
        exit(1);
     }
     
     do
     {
         fin1 >> num;
         count11++;
     }while(!fin1.eof());
     fin1.close();
}

void calc_median(ifstream& fin2, int& count)
{     
     int location = 0, numbers[count], median, num; 
     
     fin2.open("myMedian.txt");
     if(fin2.fail())
     {
        cout << "File opening failed"<<endl;
        exit(1);
     }
     
     if(count%2 == 0)
     {
        location = count / 2;
        for(int i = 0; i < count; i++)
        {
           fin2 >> num;
           numbers[i] = num;
        }
        median = (numbers[location] + numbers[location + 1])/2;
     }
     else
         median = numbers[location + 1];
         
     cout << "The median is equal to: "<< median <<endl;
     
}

[bluecoder]

is there any negative value in the file ?

[ayanda83]

No, there is no negative number in the file.

[Peter87]

If count is 14 count%2 == 0 is false so the the else part in calc_median will run: median = numbers[location + 1]; Problem here is that location is still zero and you have not written anything to the array so it will only contain garbage values, possibly negative.

[ayanda83]

thank you for your response Peter87, but i thought the line numbers[i] = num; in calc_median function writes into the array.

[Peter87]

Yes but only if count is odd.

[vin]

Isn't count%2 == 0 true for count an even number?

My test loops through the else branch in calc_median since for an input file of 14 integers count1 after read_file is 15.

[Peter87]

vin, you are right. But if the count variable is wrong it is still the same problem. looping until .eof() often do one iteration too much. Try replace the do-while loop in read_file with:

while(fin1 >> num)
{
    count11++;
}