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#include <iostream>
using std :: cout;
using std :: cin;
using std :: endl;
using std :: ios;
#include <iomanip>
using std :: setprecision;
#include <cmath>
#include <cstdlib>
#include <string>
using std :: string;
void displayArray(int*, int, int);
double mean(int*, int);
int main()
{
int allocated_size = 25;
int current_size = 10;
int re_allocated_size=0;
int *iUserPtr=0; // for user_array
int *iReallocatePtr=0; // for re-allocation array
int *itPtr; // traversal pointers
// to dynamic allocate the (user_array) iUserPtr
iUserPtr = new int[allocated_size];
// initialize the user array for the first time
itPtr = iUserPtr; // use the traversal pointer
for(int i=0; i<allocated_size-1; i++)
*(itPtr+i) = 0;
*(itPtr+(allocated_size-1)) = -1; // mark the last item
for(int i=0; i<current_size; i++)
*(itPtr+i) = allocated_size -i;
for (int i=0; i<allocated_size; i++)
*(iUserPtr+i)= *(itPtr+i);
string user_input, buf1, buf2, buf3;
int change, value;
bool stay = true;
while(stay) //as long as the user doesn't choose q, the program will continue to go back to menu
{
cout << " ----------- COMMAND MENU ------------"<<endl
<< " 1 - display user_array and its size\n"
<< " 2 - modify user_array content\n"
<< " 3 - modify user_array size\n"
<< " 4 - mean of user_array\n"
<< " q - quit\n\n"
<< " --> Enter your choice: ";
cin >> user_input;
cin.ignore();
if(user_input.size() == 1)
{
char ch = user_input[0];
// displaying user_array
if (ch == '1')
{
displayArray(iUserPtr, current_size, allocated_size);
}
// modify the user_array[]
if (ch == '2')
{
int location;
cout << "Enter a location between 1 and "<<current_size<<": ";
cin >> buf1; location=atoi(buf1.c_str());
change=*(iUserPtr+(location-1));
cout << "The current value is "<< change <<". What is the new value? ";
cin >> buf2; value=atoi(buf2.c_str());
if(location>0 && location <=current_size)
*(iUserPtr+(location-1)) = value;
cout <<endl;
}
// modify the size of user_array[]
if (ch == '3')
{
int requested_size;
cout << "new working size? ";
cin >> requested_size;
cin.ignore();
// case 1. need for memory grows beyond 80% allocated
if(requested_size > allocated_size*8/10)
{
// allocate new 4X the old allocated
re_allocated_size = allocated_size*4; //pattern to grow
iReallocatePtr = new int[re_allocated_size];
cout << "The new allocated size is "<< re_allocated_size << endl;
// initialize new arrays to display work space
itPtr = iReallocatePtr;
for(int i=0; i<re_allocated_size; i++)
*itPtr++ = re_allocated_size -i;
itPtr = iReallocatePtr;
for(int i=0; i<re_allocated_size; i++)
cout << *itPtr++ << " ";
cout << endl;
itPtr = iReallocatePtr;
for(int i=0; i<re_allocated_size-1; i++)
*(itPtr+i)= 0;
*(itPtr+(re_allocated_size-1)) = -1; // mark the last item
for(int i=0; i<requested_size; i++)
*(itPtr+i) = re_allocated_size -i;
for (int i=0; i<re_allocated_size; i++)
*(iReallocatePtr+i)= *(itPtr+i); // transfering to new
allocated_size = re_allocated_size;
}
else if(requested_size < (allocated_size/10.0))
{
// to re_allocate new array size as 1/4 allocated
re_allocated_size = allocated_size/4; //Patern to shrink
iReallocatePtr = new int[re_allocated_size];
cout << "The new allocated size is "<< re_allocated_size << endl;
itPtr = iReallocatePtr;
for(int i=0; i<re_allocated_size; i++)
*itPtr++ = re_allocated_size -i;
itPtr = iReallocatePtr;
for(int i=0; i<re_allocated_size; i++)
cout << *itPtr++ << " ";
cout << endl;
itPtr = iReallocatePtr;
for(int i=0; i<re_allocated_size-1; i++)
*(itPtr+i)= 0;
*(itPtr+(re_allocated_size-1)) = -1; // mark the last item
for(int i=0; i<requested_size; i++)
*(itPtr+i) = re_allocated_size -i;
for (int i=0; i<re_allocated_size; i++)
*(iReallocatePtr+i)= *(itPtr+i); // transfering to new
allocated_size = re_allocated_size;
}
// case 3. need for memory requires no re_allocation
else //allocated size is not changed when the requested size is below 80% and above 10%
{
iReallocatePtr = new int[re_allocated_size];
re_allocated_size = allocated_size;
itPtr = iReallocatePtr; // use the traversal pointer
for(int i=0; i<re_allocated_size-1; i++)
*(itPtr+i) = 0;
*(itPtr+(allocated_size-1)) = -1; // mark the last item
for(int i=0; i<requested_size; i++)
*(itPtr+i) = allocated_size -i;
for (int i=0; i<re_allocated_size; i++)
*(iReallocatePtr+i)= *(itPtr+i);
allocated_size = re_allocated_size;
}
// all cases to update the current_size as requested
current_size = requested_size;
displayArray(iReallocatePtr, current_size, allocated_size);
for (int i=0; i<allocated_size; i++)
*(iUserPtr+i)= *(iReallocatePtr+i);
}
//calculation of mean
if (ch == '4')
{
cout << std::fixed << std::showpoint ;
cout << "The mean of the integers (size of "<< current_size<<") is: " << setprecision(2)
<< mean(iUserPtr, current_size) <<"."<< endl << endl;
}
if(ch == 'q') //the program will close when the user enter q
stay = false;
}
}
return 0;
}
//********************************************************************************************************
//fuction to display the numbers in the array
void displayArray(int *arr, int elems, int allo)
{
cout << "The array is allocated with " << allo
<< "\nCurrent working size " << elems
<< "\nThe last item is marked as "
<< *(arr + allo -1)
<< "\nThe allocated array content is: ";
for(int i=0; i<allo; i++) cout << *arr++ << " ";
cout << endl << endl;
}
// function to search for mean
double mean(int *l, int s)
{
double total = 0.0;
double average = 0;
for(int i=0;i<s;i++)
total+= *(l+i); //calculate the total of numbers in user_array
average = total/s;
return average;
}
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