Thread: Help with function

here is the whole program...

Code:

//Name: Joseph Valenzuela
//Date: March 11, 2003
//Purpose: To design and implement my own program for project1.

#include <iostream.h> // For output to the screen and input from user
#include <fstream.h> // To allow input and output streams
#include <stdlib.h> // Contains exit function
#include <math.h> // Contains square root function

void compute(double& sum, double& sum_of_squares);
//Precondition:None
//Postcondition:To compute the sum and sum of squares of the numbers in the input file
double mean(int xnum, double sum);
//Precondition:Requires the amount of numbers and sum of those numbers
//Postcondition:Calculates the mean of the numbers in the input file and returns the value
double variance(double sum_of_squares, int xnum, double avg);
//Precondition:Requires sum of the squares, the amount of numbers and the mean of the numbers
//Postcondition:Calculates the variance of the numbers in the input file and returns the value
double deviation(double var); 
//Precondition:Requires the variance
//Postcondition:Calculates the standard deviation of the numbers in the input file and returns the value
double median (int xnum);
//Precondition:Requires amount of numbers in input file
//Postcondition:Calculates the median of the numbers in the input file, and returns the value

void main()
{
  
  double sum,sum_of_squares,avg,var,dev,med; //Declares variables
  int xnum;
  
  
  cout <<"\nWELCOME TO THE BASIC STATISTICS PACKAGE!\n";
  
  cout << "Enter amount of numbers to be evaluated: ";
  cin >> xnum;
 
  cout.setf(ios::fixed);
  cout.setf(ios::showpoint);
  cout.precision(2);
  
  compute(sum,sum_of_squares);
  avg = mean(xnum, sum);
  cout << "The Mean price of the numbers is $" << avg << endl;
  
  med = median(xnum);
  cout <<"The median price of the numbers is $" << med << endl;

  var = variance(sum_of_squares,xnum,avg);
  cout <<"The Variance price of the numbers is $" << var << endl;
  
  dev = deviation(var);
  cout <<"The Standard Deviation price of the numbers is $" << dev << endl;
  
  
  
  
  
}

//Precondition:None
//Postcondition:To compute the sum and sum of squares of the numbers in the input file
void compute(double& sum, double& sum_of_squares)
{
  
  sum = sum_of_squares = 0;
  double in_num=0;
  ifstream input_data;
  
  input_data.open("stats.dat");
  if (input_data.fail())
    {
      cout <<"Input file could not be opened.\n";
      exit(1);
    }
  
  input_data >> in_num;
  while (!input_data.eof())
    {
      sum += in_num;
      sum_of_squares += in_num*in_num;
      input_data >> in_num;
    };
  
  input_data.close();
  
}

//Precondition:Requires the amount of numbers and sum of those numbers
//Postcondition:Calculates the mean of the numbers in the input file
double mean(int xnum, double sum)
{
  double avg=0;
  
  avg = sum/xnum;
  return(avg);
  
}

//Precondition:Requires sum of the squares, the amount of numbers and the mean of the numbers
//Postcondition:Calculates the variance of the numbers in the input file
double variance(double sum_of_squares, int xnum, double avg)
{
  
  double var=0;
  
  var = (sum_of_squares/xnum) - (avg*avg);
  return(var);
  
}

//Precondition:Requires the variance
//Postcondition:Calculates the standard deviation of the numbers in the input file
double deviation(double var)
{
  
  double dev;
  
  dev =  sqrt(var);
  return(dev);
  
}

//Precondition:Requires amount of numbers in input file
//Postcondition:Calculates the median of the numbers in the input file, and returns the value
double median (int xnum)
{
  double median,med_pos,count=0, temp;
  ifstream input_data;
  
  
    input_data.open("stats.dat");
    if (input_data.fail())
      {
	cout <<"Input file could not be opened.\n";
	exit(1);
	
	med_pos = xnum/2;
      }
    
if ((xnum%2)==0)
      {
	median=0;
	while (input_data >> temp)
	  {	
	    count++;
	    if((count==med_pos)||(count==med_pos+1))
	     	median = median + temp;
	  }
    
    median = median/2;
     
      }
   
    
    
    else if ((xnum%2)!=0) 
      {
	median=0;
	while (input_data >> temp)
	  {	
	    count++;
	    if(count==med_pos+1)
	      median = median + temp;
	  }
	median = median/2;
      }
  
  return(median);
  
  }

Hey I got it guys dont worry about it. Thanks