Finding minimum and maximum points coordinates with C++ - c++

Question

I have a text file that include X,Y,Z coordinates of points. My aim is finding minimum and maximum points and write it another file. For this aim I write a distance function. The points that have maximum distance is minimum and maximum points. here is my code. It works but it does not calculate or write anything.
#include <iostream>
#include<fstream>
#include <math.h>
using namespace std;
double distance (float X1, float Y1, float Z1, float X2, float Y2, float Z2)
{
return sqrt(pow((X2-X1),2)+ pow((Y2-Y1),2)+pow((Z2-Z1),2));
}
int main ()
{
float x1, y1, z1,x2, y2,z2;
ifstream file("D:\\points.txt");
ofstream result ("D:\\result.txt");
double bigdistance=0;
if (file.is_open())
{
while (!file.eof())
{
file>>x1>>y1>>z1;
while (!file.eof())
{
file>>x2>>y2>>z2;
double d= distance (x1,y1,z1,x2,y2,z2);
if (bigdistance<d)
{
bigdistance=d;
result<<x1<<y1<<z1<<endl<<x2<<y2<<z2;
}
}
}
}
else cout <<"cannot open file";
system ("PAUSE");
return 0;
}

Answer 1

A couple of suggestions:
while (file >> x1 >> y1 >> z1 >> x2 >> y2 >> z2) {
}
will read your input and stop if any of the reads failed.
You will want to read the entire input and store it in a vector of points, or similar. Then, you can use two nested loops to iterate over each pair of points. Right now, your programs assumes that the input file contains all pairs. That is, each point is read multiple times form the input, in the inner loop.
There are also algorithms that are faster than quadratic, and you might need those if you have more than a couple thousand input points. See for example this StackOverflow question.

Answer 2

#include <iostream>
#include<fstream>
#include <math.h>
using namespace std;
enter code here`{
for (int i = 1; !f1.eof(); i++)
{
int x1, y1, x2, y2, x3, y3, x4, y4);
read(f1, x1, y1, x3, y3);
x2 = x3;
y2 = y1;
x4 = x1;
y4 = y3;
if (y4 > y1)
{
a = y1 - y4;
}
else
a = y4 - y1;
if (x4 > x3)
{
b = x4 - x3;
}
else
b = x3 - x4;
}
}