Question 4: implement class methods [8]

Suppose we are provided with the class definition shown below: 
class IntArr {
   public:
      IntArr();                   // Note: initially the array is NULL
      ~IntArr();                  // deallocates the array
      bool Alloc(int N, int v);   // allocates an array of N integers,
                                  //    initializes the values to v
      int getSum();               // returns the sum of the array elements
      bool set(int v, int p);     // if p is valid this stores value v in 
                                  //      position p and returns true
                                  //   otherwise returns false
      bool lookup(int p, int &v); // if p is valid this sets v to the value 
                                  //   stored in position p and returns true
                                  // otherwise returns false
   private:
      int ArrSize;   // the size of the allocated array
      int *Arr;      // the allocated array
};
Provide implementations for both the Alloc and getSum methods of the class.