Stats Calculator

Here is an example of how we can use the dynamic array to implement the statistics calculator.

stats-calc.cpp

#include <stdio.h>
#include "dynamic-array.hpp"

/**
 * Read an integer from the user
 *
 * @param prompt the message to show the user
 * @returns the integer entered
 */
int read_integer(const char *prompt)
{
  int result = 0;

  printf("%s", prompt);
  while (scanf(" %d", &result) != 1) // Read value, and try to convert to int
  {
    // Convert failed, as input was not a number
    scanf("%*[^\n]"); // Read past the end of the current line
    printf("Please enter a whole number.\n");
    printf("%s", prompt);
  }

  return result;
}

/**
 * Read a double value from the user
 *
 * @param prompt the message to show the user
 * @returns the double entered
 */
double read_double(const char *prompt)
{
  double result = 0;

  printf("%s", prompt);
  while (scanf(" %lf", &result) != 1) // Read value, and try to convert to int
  {
    // Convert failed, as input was not a number
    scanf("%*[^\n]"); // Read past the end of the current line
    printf("Please enter a whole number.\n");
    printf("%s", prompt);
  }

  return result;
}

/**
 * Populate the array with values entered by the user
 *
 * @param data the array of values
 */
void populate_array(dynamic_array<double> *data)
{
  int size = read_integer("How many values do you want to enter? ");

  for (int i = 0; i < size; i++)
  {
    add(data, read_double("Enter value: "));
  }
}

/**
 * Output the values in the array
 *
 * @param data the array of values
 */
void print(const dynamic_array<double> *data)
{
  for (int i = 0; i < data->size; i++)
  {
    printf("%d: %lf\n", i, get(data, i, 0.0));
  }
}

/**
 * Calculate the sum of the values in the array
 *
 * @param data the array of values
 * @return the sum of the values
 */
double sum(const dynamic_array<double> *data)
{
  int i;
  double result = 0;

  for (i = 0; i < data->size; i++)
  {
    result += get(data, i, 0.0);
  }

  return result;
}

/**
 * Calculate the mean of the values in the array
 *
 * @param data the array of values
 * @returns the mean of the values
 */
double mean(const dynamic_array<double> *data)
{
  if (data->size > 0)
    return sum(data) / data->size;
  else
    return 0;
}

/**
 * Calculate the largest value in the array
 *
 * @param data the array of values
 * @returns the largest value, or 0 if there are no values
 */
double max(const dynamic_array<double> *data)
{
  // Ensure there is data
  if (data->size == 0)
    return 0;

  // Assume the first value is the largest
  double result = get(data, 0, 0.0);

  // Check the rest of the values
  for (int i = 1; i < data->size; i++)
  {
    if (get(data, i, 0.0) > result)
    {
      result = get(data, i, 0.0);
    }
  }

  return result;
}

/**
 * Add a value to the array
 *
 * @param data the array of values
 */
void add_data(dynamic_array<double> *data)
{
  double value = read_double("Enter a value to add: ");

  if (!add(data, value))
  {
    printf("Sorry, out of memory\n");
  }
}

/**
 * Remove a value from the array
 *
 * @param data the array of values
 */
void remove_value(dynamic_array<double> *data)
{
  print(data);

  int index = read_integer("Enter the index of the value to remove: ");

  if (index >= 0 && index < data->size)
  {
    for (int i = index; i < data->size - 1; i++)
    {
      set(data, i, get(data, i + 1, 0.0));
    }
    resize(data, data->size - 1);
  }
  else
  {
    printf("Sorry, that is not a valid index.\n");
  }
}

// Implements a statistics calculator. The program reads in values entered by the user
// and then calculates the sum, mean, variance, and max
int main()
{
  dynamic_array<double> *data = new_dynamic_array<double>(10);

  populate_array(data);

  printf("\nCalculating statistics...\n\n");

  printf("Sum:        %4.2f\n", sum(data));
  printf("Mean:       %4.2f\n", mean(data));
  printf("Max:        %4.2f\n", max(data));

  add_data(data);

  print(data);

  remove_value(data);

  print(data);

  delete_dynamic_array(data);

  return 0;
}