Thread: derived classes

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

class Stack {
      public:
             class Underflow { };
             class Overflow { };
             class Bad_Size { };
             
             virtual void push(char c) = 0;
             virtual char pop() = 0;
};

class Array_stack : public Stack {
      char *p;
      int max_size;
      int top;
      public:
             Array_stack(int s); 
             ~Array_stack();
             
             void push(char c);
             char pop();
};

Array_stack::Array_stack(int s) //cant compile
{
            if(s > 10000)
                 throw Bad_Size();
            p = new char[s];
            max_size = s;
            top = 0;                      
}
int main()
{
     
      
      
}

Why wont this work?

How can i define a constructor that's declared inside a derived class, but i want to define it outside of the class itself?

What is the compile error?