struct, function and pointer problem

[kkl19880913]

Hi, i am learning c++ by myself . I am trying to write a code to find slop using struct, function and pointer.
In the main function i really get lost.

Any help will be appreciate.

 #include <iostream>

using namespace std;

struct king
{
	double x1,x2;
	double y1,y2;
};

double distance (king*ptr)
{
	return (ptr->y2 - ptr->y1) / (ptr->x2 - ptr->x1);
}

int main()
{
	
	
	
	cout <<"Enter  x2 ";
	cin >>x2;
	cout <<"Enter x1";
	cin >>x1;
	cout <<"Enter y2 ";
	cin >>y2;
	cout >>"Enter y1";
	cin >>y1;
	
	
	
}