Class with an array from another class

[Sixx]

Im trying to make a class with an array from another class.
Obj

class Obj {
int i;
public:
Obj ();// default constructor; 
Obj (int j) {i=j;};
};

Array

 class Arr {
Obj* P;  //??
int length;
public:
Arr (int i) {
length=i; 
P=new Obj[length];};

With ?? is the main problem because i have tried different combinations with Obj** P etc, but it only creates one instance of the class Obj.
The only thing that created multiple instances was Obj* P[10] but I can't use constant because i don't know in advance how much Obj I need. Also I am not alowed to use vectors. Please help because I'm stuck on this for 36 now.

[coder777]

With ?? is the main problem

Why's the problem? You're right that's the way dynamic arrays are declared. Use delete[] to destroy (in your destructor)

[ne555]

(don't just try random combinations) If the array cannot change its size you could try this

template <int n>
class Arr{
private:
  Obj P[n];
};
//...
Arr<10> array;

Sorry it's not dynamic.

[Sixx]

The problem is that he creates array of Obj but with only one member. If I try to input 3, 2, 1 in a loop, he will just create one Obj with value 3 and the rest he will ignore. There is nothing wrong with the loop because I see in the debugger that he initalize P with space for only one Obj, and I want to have pointer array of n Obj.

I can't initialize it with P[n] because n must be a constant and i dond now what that number will be at the begining.

The only time it has correctly created array is with Obj* P[10] where he created array P with space for 10 Obj.

Edit: I you didn't understand me he will create array P but that array will just be P[0].

[ne555]

The creation is fine. Post when you use it.

[Sixx]

In main i will do

 int main() {
int i=13;  // i is the length that i will calculate before calling Arr
Arr PO(i);
PO.work();
PO.read();
}

where work and read will be defined as

 void Arr::work {
for (int i=0; i<length; i++) {
int j;
cin >> j;
P[i]= Obj(j) 

void Arr::read () {
for (int i=0; i<length; i++) 
cout << P[i].give(); // where give is a method from Obj with { return i; } 

There is something wrong with the creation because he will just make P[0].

[Sixx]

I'm sorry i have misunderstud debuger and the pointer this.
What I wrote is the correct way to create an array.

Thank you for your time.