My list class

// Program Description: This is a header file for the list class

#ifndef LIST_H
#define LIST_H

#include <iostream.h>

const int SIZE = 20;

class List{
 public:
  List();
  void Show();
  bool Insert(int value);
  bool Insert(int value, int pos);
  bool Delete(int pos);
  int Size();
  int Sum();
  float Average();
  int Odds();
  int HowMany(char value);
  int Between(int low,int high);
  int WhereIs(int value);
  void Clear();
 private:
  int list_array[SIZE];// the container -- an array of 20 integers
  int element;// a pointer that keeps track of the position in array
};

#endif

/*-------------------------------------list.cpp------------------------------------------*/

#include <iostream.h>
#include "list.h"

List::List()
  // constructor for list object - has to create the list object and print out message that
  // object has been instantiated
{
  element = 0;
  cout << "Creating List Object\n";
}

void List::Show()
  // if list is empty, output message
  // else show elements in list
{
  if (element <= 0)
    cout << "List is empty\n";
  else if (element >= SIZE)
    cout << "List is full\n";
  else{
    for (int i = 0; i < element; i++)
      cout << list_array[i] << " ";
    cout << "\n";
  }
}
bool List::Insert(int value)
  // Inserts a number at the end of the list(if there is enough room)
{
  if (element < SIZE){
    list_array[element] = value;
    element = element++;
    return true;
  }
  else{
    cout << "*** Invalid list position number\n";
    return false;
  }
}
bool List::Insert(int pos, int value)
  // inserts a number in the list, possibly in the middle(if room, and if valid position given)
{
  if (pos <= (element+1)){
    // In order to insert another value, we need atleast one more free space
    if (((element+1) < SIZE) && (pos > 0)){

      // starting at element, begin  moving every element one space to the right
      for(int i = (element+1); i <= pos; i--)
        list_array[i + 1] = list_array[i];

      // at pos, insert new value;
      list_array[pos] = value;

      // increment element
      element = element + 1;
      return true;
    }
  }
  else {
    cout << "*** Invalid position number\n";
    return false;
  }
}
bool List::Delete(int pos)
  // delete a value from the list(given a position)
{

  if ((element < 0) && (element > SIZE)){
    cout << "*** Invalid list position number";
    return false;
  }

  else{
    // shift value at pos + 1 and so on to the left
    for (int i = element; i > pos; i--)
      list_array[i] = list_array[i + 1];

    // decrease element by one
    element = element - 1;

    return true;
  }
}
int List::Size()
  // returns the size of list
{
  return element;
}

int List::Sum()
  // returns the sum of the values in the list
{
  int sum = 0;
  for (int i = 0; i < element; i++)
    sum += list_array[ i ];
  return sum;
}

float List::Average()
  // returns the average of the values in the list
{
  float sum = Sum();
  float size = Size();
  float average = sum/size;
  return average;
}
int List::Odds()
  // counts up and returns how many odd numbers in the list
{
  int odd_count = 0;
  for (int i = 0; i <= element; i++){
    if ((list_array[i] % 2) == 1){
      odd_count++;
    }
  }
  return odd_count;
}

int List::HowMany(char value)
  // counts up and returns how many occurences of a given value(should work for any parameter value)
{
  int how_many_counter = 0;
  for (int i=0; i < element; i++){
    if (list_array[i] == value)
      how_many_counter++;
  }
    return how_many_counter;
}
int List::Between(int low,int high){
  int between = 0;
  int value;
  for(int i = 0; i < element; i++){
    value = list_array[i];
    if((value >= low) && (value <= high))
      between++;
  }
  return between;
}

int List::WhereIs(int value)
  // returns the position of the first occurence of a given value(or returns 0, if not found)
{

  int num;   // This variable tells us what number is in array_list[i]
  // This is just a counter to capture the position we are on
  int pos_counter = 0;

  for (int i = 0; i <= element; i++){
    num = list_array[i];
    if (num == value)
      pos_counter = (i + 1);  // capture the array number + 1
  }
  return pos_counter;
}

void List::Clear()
  // resets the list object to represent an empty list
{
  element = 0;
}

bool List::Insert(int pos, int value)
  // inserts a number in the list, possibly in the middle(if room, and if valid position given)
{
  if (pos <= (element+1)){      //here u should check if the position is one less than the SIZE constant instead
    // In order to insert another value, we need atleast one more free space
    if (((element+1) < SIZE) && (pos > 0)){     //should be (element + 1) <= SIZE , since size is the max number of elements

      // starting at element, begin  moving every element one space to the right
      for(int i = (element+1); i <= pos; i--) //your starting PAST the last index with (i = (element + 1)), should (element - 1)
        list_array[i + 1] = list_array[i];      // and i >= since your moving backwards

      // at pos, insert new value;
      list_array[pos] = value;

      // increment element
      element = element + 1;
      return true;
    }
  }
  else {
    cout << "*** Invalid position number\n";
    return false;
  }
}

bool List::Insert(int pos, int value)
{       // if we have space and the position is positive
        if((element < (SIZE - 1))&&(pos >= 0)&&(pos <=19))
        {
                //start from furthest element to right and shift each element one to the right
                for(int x = (elem - 1); x >= pos; x--)
                {
                        list_array[x + 1] = list_array[x];
                }
                //now replace the desired position
                list_array[pos] = value;
                //increment list size
                element++;
                return true;
        }
        else    // error
        {
                cerr << "invalid position\n";
                return false;
        }
}

1 2 3 4 5 10 25 40 50 65
// the first number, '1' is in position 1, not 0