taking the elements of array whitin a structure - c++

Question

here is my code, as you can see I used arrays of structures. The question is how should I take the arrays element by user directly? You can see below how the elements are given to the program before execution.
any help will be appericiated.
#include<iostream>
#include<math.h>
using namespace std;
struct Data
{
int x, y;
};
double interpolate(Data f[], int xi, int n)
{
double P = 0;
for (int i = 0; i<n; i++)
{
double p= f[i].y;
for (int j = 0;j<n;j++)
{
if (j != i)
p =p*(xi - f[j].x) / (f[i].x - f[j].x);
}
P += p;
}
return P;
}
int main()
{
Data f[] = { { 0,2 },{ 1,3 },{ 2,12 },{ 5,147 }};
cout << "Value of f(3) is : " << interpolate(S, 3, 4) << endl;
system("pause");
return 0;
}

Answer 1

#include<iostream>
#include<math.h>
using namespace std;
struct Data
{
int x, y;
};
double interpolate(Data f[], int xi, int n)
{
double P = 0;
for (int i = 0; i<n; i++)
{
double p= f[i].y;
for (int j = 0;j<n;j++)
{
if (j != i)
p =p*(xi - f[j].x) / (f[i].x - f[j].x);
}
P += p;
}
return P;
}
int main()
{
int input[8];
cout << "Enter first value: \n";
cin >> input[0];
cout << "Enter second value: \n";
cin >> input[1];
cout << "Enter third value: \n";
cin >> input[2];
cout << "Enter fourth value: \n";
cin >> input[3];
cout << "Enter fifth value: \n";
cin >> input[4];
cout << "Enter sixth value: \n";
cin >> input[5];
cout << "Enter seventh value: \n";
cin >> input[6];
cout << "Enter eighth value: \n";
cin >> input[7];
Data f[] = {{input[0], input[1]}, {input[2], input[3]}, {input[4], input[5]}, {input[6], input[7]}};
cout << "Value of f(3) is : " << interpolate(f, 3, 4) << endl;
system("pause");
return 0;
}