ITK  4.9.0
Insight Segmentation and Registration Toolkit
WikiExamples/SimpleOperations/DistanceBetweenPoints.cxx
#include "itkPoint.h"
#include <iostream>
#include <string>
int main(int, char *[])
{
p0[0] = 0.0;
p0[1] = 0.0;
p0[2] = 0.0;
p1[0] = 1.0;
p1[1] = 1.0;
p1[2] = 1.0;
double dist = p0.EuclideanDistanceTo(p1);
std::cout << "Dist: " << dist << std::endl;
return EXIT_SUCCESS;
}