Question

Problem 3 (25 points) Redo problem l using an array generated from the method new to dynamically allocate memory for your array after you read in the first integer number in the file. This tell you how big to make the array Problem 4 (25 points) Redo problem 1 using the STL container vector. This time the test file will just contain decimal numbers. The first integer will not be there. The loop reading the file should stop when it detects the end of the file.

Here is the Prompt for problem 1:

Write a C++ program that reads in a test file. The first number in the file will be an integer, and will indicate the amount of decimal numbers to follow. Once you have the read the numbers from the file into an array then compute the following properties on the set of numbers: the sum, the average (mean), the variance, the standard deviation, and the median. Don’t try to do the entire program at once. Build a little, test a little. Your program should contain 5 functions (methods). One method to compute the sum, a method to compute the average (mean), a method to compute the variance, a method to compute the standard deviation, and finally a method to compute the median. Think carefully about the parameters for each method. For example the method double Sum(double[] nums) might take an array as a parameter, and have a return type of double in order to return the sum of the array. The method double Average(double sum, int n) might have a parameter for sum, and a parameter for the number of numbers in the array, and a return type of double to return the decimal average. The method to compute the median should work regardless of whether n is even or odd, where n is the length of the array.

Example for an odd sized array: {5, 7, 8, 9, 2}

Answer 1

Here I provided with the c++ codes of problem3 and problem4 as asked.

Code For PROBLEM 3

#include <iostream>
#include <fstream>
#include <algorithm>
#include <math.h>
using namespace std;

double arraySum(double* a, int n){
   double sum = 0;
   for(int i=0;i<n;i++){
       sum+=a[i]; //update sum
   }
   return sum;
}

double mean(double *a, int n){
   double m;
   m = arraySum(a,n)/n; // calculates the sum and divides by n
   return m;
}

double median(double *a,int n){
   double med = 0;
sort(a,a+n);
// if number of elements are even
if(n%2 == 0)
med = (a[(n-1)/2] + a[n/2])/2.0;
// if number of elements are odd
else
med = a[n/2];
  
return med;
}

double sd(double* a,int n){
   double sum = 0.0, m, standardDeviation = 0.0;

int i;
m = mean(a,n);

for(i=0; i<n; ++i)
standardDeviation += pow(a[i] - m, 2);

return sqrt(standardDeviation/n);
}

double variance(double* a,int n){
   double sum = 0.0, m, v = 0.0;

int i;
m = mean(a,n);

for(i=0; i<n; ++i)
v += pow(a[i] - m, 2);

return v/n;
}

int main() {

   int n; //Number of decimal numbers to follow

   fstream file("test.txt");
   file >> n; // similar to cin but this takes input from the file instead of console

   double* a = NULL; // Pointer to int, initialize to nothing.
   a = new double[n]; // Allocate n ints and save ptr in a.
   for (int i=0; i<n; i++) {
   file >> a[i] ; // Initialize all elements to zero.
   }

   //Remove this part of the code(below 5 lines) if you don't want to print given numbers
   printf("The given numbers are \n");
   for (int i=0; i<n; i++) {
   cout<< a[i] <<endl;   
   }
   cout<<endl;

   cout << "The mean of given numbers is " << mean(a,n) << endl;
   cout << "The median of the given numbers is " << median(a,n) << endl;
   cout << "The Standard Deviation of given numbers is " << sd(a,n) << endl;
   cout<< "The Variance of given numbers is " << variance(a,n) <<endl;

return 0;
}

CODE FOR PROBLEM 3 ENDS HERE

CODE FOR PROBLEM 4

#include <iostream>
#include <fstream>
#include <algorithm>
#include <math.h>
#include <vector>
using namespace std;

double arraySum(std::vector<double> a){
   int n = a.size();
   double sum = 0;
   for(int i=0;i<n;i++){
       sum+=a[i]; //update sum
   }
   return sum;
}

double mean(std::vector<double> a){
   int n = a.size();
   double m;
   m = arraySum(a)/n; // calculates the sum and divides by n
   return m;
}

double median(std::vector<double> a){
   int n = a.size();
   double med = 0;
sort(a.begin(),a.end());
// if number of elements are even
if(n%2 == 0)
med = (a[(n-1)/2] + a[n/2])/2.0;
// if number of elements are odd
else
med = a[n/2];
  
return med;
}

double sd(std::vector<double> a){
   int n = a.size();
   double sum = 0.0, m, standardDeviation = 0.0;

int i;
m = mean(a);

for(i=0; i<n; ++i)
standardDeviation += pow(a[i] - m, 2);

return sqrt(standardDeviation/n);
}

double variance(std::vector<double> a){
   int n = a.size();
   double sum = 0.0, m, v = 0.0;

int i;
m = mean(a);

for(i=0; i<n; ++i)
v += pow(a[i] - m, 2);

return v/n;
}

int main() {

   double k;

   fstream file("test.txt");
  
   std::vector<double> v; //declare vector
   while(file >> k){
       v.push_back(k); //while there are numbers in the file input them
   }

   //Remove this part of the code(below 5 lines) if you don't want to print given numbers
   printf("The given numbers are \n");
   vector < double> :: iterator it;
   for(it=v.begin();it!=v.end();it++){
       cout<<*it<<endl;
   }
   cout<<endl;

   cout << "The mean of given numbers is " << mean(v) << endl;
   cout << "The median of the given numbers is " << median(v) << endl;
   cout << "The Standard Deviation of given numbers is " << sd(v) << endl;
   cout<< "The Variance of given numbers is " << variance(v) <<endl;

return 0;
}

CODE FOR PROBLEM 4 ENDS HERE

The above two codes are implemented as asked, please do change the name of the file from which you are reading before you run the code. Here I also attached the screenshots of some test runs.

Output for question 3

The given numbers are 1.3423 23.3423 2.23432 3.32423 5.4542 The mean of given numbers is 7.13947 The median of the given numbers is 3.32423 The Standard Deviation of given numbers is 8.21701 The Variance of given numbers is 67.5193

Output for question 4

The given numbers are 43.323 43.3432 23.234 23.242 23.2343 4.42332 3.23432 34.342 42.44 The mean of given numbers is 26.7574 The median of the given numbers is 23.242 The Standard Deviation of given numbers is 14.6905 The Variance of given numbers is 215.812

Thanks, comment for any queries.