C ++ to variable length array class int

/ ************************************************* *********************** 
* function: 1 can specify the number of array elements in the object initialization 
* 2: play can dynamically add elements in the array 
* 3: use of such, do not worry about dynamic memory allocation, release problems 
* 4: arrays can be used as a dynamic array is used as the class objects, such elements can be accessed by the index.　
************************************************** ************************************************************ / 


#include <the iostream>  
#include <CString>
 the using  namespace STD; 

class CArray- 
{ 
    
    Private :
         int size;
         int * PTR;
     public : 
        CArray-( int S = 0 ); 
        CArray-( const CArray &);
        
        void push_back(int v);
        CArray & operator=(const CArray &);
        int length();
        int &operator[](int i)
        {
            return ptr[i];
        }
        ~CArray();    
};


int CArray::length()
{
    return size;
}
//CArray::CArray(int s=0):size(s)
CArray::CArray(int s):size(s)
{
    if(s==0) 
        PTR = NULL;
     the else 
        PTR = new new  int [S];     
} 
CArray-CArray-:: ( const CArray-S &) // NOTE parameter to const, prevent accidental changes 
{
     IF (s.size == 0 ) 
    { 
        size = 0 ; 
        PTR = NULL;
         return ; 
    } 
    PTR = new new  int [s.size]; 
    the memcpy (PTR, s.ptr, the sizeof ( int ) * s.size); 
    size =s.size;
}
void CArray::push_back(int v)
{
    if(ptr)
    {
        int * tempPtr=new int[size+1];
        memcpy(tempPtr,ptr,size*sizeof(int));
        delete [] ptr;
        ptr=tempPtr;
    }
    else
        ptr=new int[1];
    ptr[size++]=v;
    
}
CArray & CArray::operator=(constS & CArray-) // NOTE parameter const. 
{
     IF (s.ptr == PTR)
         return * the this ;
     IF (PTR) // must pay attention to prevent the null pointer delete 
        delete [] PTR;
     IF (s.ptr) 
    { 
        PTR = new new  int [s.size]; 
        the memcpy (PTR, s.ptr, s.size * the sizeof ( int )); 
        size = s.size; 
    } 
    the else 
    { 
        PTR = NULL; 
        size = 0  ;
    }
    return *this;
        
}
CArray::~CArray()
{
    if(ptr)
        delete [] ptr;
}


int main()
{
    CArray a;
    for(int i=0;i<5;i++) 
        a.push_back(i);
    //a[0]=11111;
//    for(int i=0;i<a.length();i++)
//        cout<<a[i]<<" ";
//    cout<<"aaaa\n";
    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]<<" ";
    } 
     
    return 0;
}