"C ++ Programming design POJ" "WEEK4 operator overloading," "class variable length integer array"

CArray a2(a1);

If you are using the default copy constructor, copy only the member variables

a2.ptr = a1.ptr shallow copy garbage is

= An assignment should override shallow copy deep copy

#include<iostream>
using namespace std;

class CArray
{
    int size; // number of array elements 
    int * PTR; // points to a dynamically allocated array 
public :
    CArray-( int S = 0 ); // S representative of the number of array elements 
    CArray-(& CArray-A); // Copy constructor 
    ~ CArray-();
     void push_back ( int v); // for adding one end of the array element v 
    & CArray- operator = ( const CArray-a &); // for assignment between an array of objects
    
    int length() { return size; }
    int & CArray::operator[](int i)
    {
        return ptr[i];
    }

}; 
CArray::CArray(int s) :size(s)
{
    if (s == 0)
        ptr = NULL;
    else
        ptr = new int[s];
}
CArray::CArray(CArray & a)
{
    if (!a.ptr)
    {
        ptr = NULL;
        size = 0;
        return;
    }
    ptr = new int[a.size];
    memcpy(ptr, a.ptr, sizeof(int) * a.size);
    size = a.size;
}
CArray :: ~ CArray ()
{
    if (ptr)
        delete[] ptr;
}
CArray& CArray::operator= (const CArray& a)
{
    IF (PTR == a.ptr)
         return * the this ;
     IF (a.ptr == NULL) // if there is a empty array 
    {
         IF (PTR)
             Delete [] PTR;
        ptr = NULL;
        size = 0;
        return *this;
    }
    IF (size <a.size) // if the original space is large enough, would not allocate new space 
    {
         IF (PTR)
             Delete [] PTR;
        ptr = new int[a.size];
    }
    memcpy(ptr, a.ptr, sizeof(int)*a.size);
    size = a.size;
    return *this;
} // CArray & CArray::operator=(const CArray & a)

void CArray::push_back(int v)
{ // add an element to the end of the array 
    IF (PTR)
    {
        int * = tmpPtr new new  int [size + . 1 ]; // reallocate space 
        the memcpy (tmpPtr, PTR, the sizeof ( int ) * size); // copy of the original contents of the array 
        Delete [] PTR;
        ptr = tmpPtr;
    }
    else
        ptr = new int[1];
    PTR [size ++] = V; // Add a new array element 
}
 int main () // To write the variable-length integer array type, so that it can be used as follows: 
{
    CArray to;
    for (int i = 0; i < 5; ++i)
        a.push_back(i);
    CArray a2, a3;
    a2 = a;
    for (int i = 0; i < a.length(); ++i)
        cout << a2[i] << " ";
    a2 = a3;
    for (int i = 0; i < a2.length(); ++i)
        cout << a2[i] << " ";
    cout << endl;
    a[3] = 100;
    CArray a4 (a);
    for (int i = 0; i < a4.length(); ++i)
        cout << a4[i] << " ";
    while (1);
    return 0;
}