Source code:

//program to find the sum of first and last element of
//an array, using new and delete operators
#include <iostream>
using namespace std;
int main(){
    float *aptr, sum;// pointer to allocate memory for an array
    int n; // reading size of an array

    //read array size
    cout<<"Enter the size of an array:";
    cin>>n;
    aptr = new float[n]; //allocate memory

    cout<<"Enter array elements:";
    for(int i = 0; i < n; i++){
        cin>>*(aptr + i); //reading array elements
    }

    sum = *(aptr) + *(aptr + n -1);
    cout<<"Sum of first and last emem="<<sum<<endl;

    return 0;
}

Sample run:

Enter the size of an array:5
Enter array elements:1.1
2.2
3.3
4.4
5.5
Sum of first and last emem=6.6