Go: package main

import (
	"fmt"
	"math"
)

func main() {
	var n int
	fmt.Scan(&n)
	for i := 0; i < n; i++ {
		var xa, ya, ra, xb, yb, rb float64
		fmt.Scan(&xa, &ya, &ra, &xb, &yb, &rb)
		// println(xa, ya, ra, xb, yb, rb)
		dis := math.Sqrt((xa-xb)*(xa-xb) + (ya-yb)*(ya-yb))
		if dis + ra < rb {
			fmt.Println(-2)
		} else if dis + rb < ra {
			fmt.Println(2)
		} else if dis > rb + ra {
			fmt.Println(0)
		} else {
			fmt.Println(1)
		}
	}
}

C++: #include<bits/stdc++.h>
using namespace std;

typedef long long int ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pair<int, int> > vii;
#define rrep(i, m, n) for(int (i)=(m); (i)<(n);  (i)++)
#define erep(i, m, n) for(int (i)=(m); (i)<=(n); (i)++)
#define  rep(i, n)    for(int (i)=0; (i)<(n);  (i)++)
#define rrev(i, m, n) for(int (i)=(n)-1; (i)>=(m); (i)--)
#define erev(i, m, n) for(int (i)=(n); (i)>=(m); (i)--)
#define  rev(i, n)    for(int (i)=(n)-1; (i)>=0; (i)--)
#define vrep(i, c)    for(__typeof((c).begin())i=(c).begin(); i!=(c).end(); i++)
#define  ALL(v)       (v).begin(), (v).end()
#define mp            make_pair
#define pb            push_back
template<class T, class S> inline bool minup(T& m, S x){ return m>(T)x ? (m=(T)x, true) : false; }
template<class T, class S> inline bool maxup(T& m, S x){ return m<(T)x ? (m=(T)x, true) : false; }

const int    INF = 1000000000;
const ll     MOD = 1000000007LL;
const double EPS = 1E-12;

template<typename T> T add(T x, T y){ if(abs(x+y) < EPS*(abs(x)+abs(y))) return 0; return x + y; }
template<typename T> inline bool semieq(T x, T y){ return abs(x - y) < EPS; }
template<typename T> inline bool semige(T x, T y){ return y - x < -EPS; }
template<typename T> inline bool semile(T x, T y){ return x - y < -EPS; }


struct Point : public complex<double>
{
public:
  Point() { this->real(0);  this->imag(0); }
  Point(const double& x, const double& y) { this->real(x);  this->imag(y); }
  Point(const complex<double> w)  { this->real(w.real());  this->imag(w.imag()); }
  inline double dot(Point p){ return (conj(*this) * p).real(); }  // ??????
  inline double det(Point p){ return (conj(*this) * p).imag(); }  // ??????
};

namespace std
{
  bool operator < (const Point& a, const Point& b)
  {
    return real(a) != real(b) ? real(a) < real(b) : imag(a) < imag(b);
  }
}
typedef vector<Point> Polygon;
#define currPoint(P, i) P[i]
#define nextPoint(P, i) P[(i+1)%P.size()]

struct Circle : Point
{
private:
  Point p;
  double r;

public:
  Circle(Point& p, double r) : p(p), r(r) {}
  Circle(double x, double y, double r) : p(Point(x, y)), r(r) {}
  inline Point center(){ return this->p; }
  inline double radius(){ return this->r; }
};

int circlesIntersection(Circle& A, Circle& B)
{
  double d = abs(A.center() - B.center());
  if(semile(d, A.radius() - B.radius())) return  1;  // B in A
  if(semile(d, B.radius() - A.radius())) return -1;  // A in B
  if(semieq(d, A.radius() - B.radius())) return  2;  // B in A????????\???
  if(semieq(d, B.radius() - A.radius())) return -2;  // A in B????????\???
  if(semige(d, A.radius() + B.radius())) return  3;  // ???????????????
  if(semieq(d, A.radius() + B.radius())) return -3;  // ?????\
  return 4;  // ????????£?????????
}

int n;
double x, y, r;

Point N(0.0, 0.0);

int main()
{
  cin >> n;

  while(n--){
    cin >> x >> y >> r;  Circle A(x, y, r);
    cin >> x >> y >> r;  Circle B(x, y, r);

    int res = circlesIntersection(A, B);
    if(res ==  1){ puts("2");   continue; }
    if(res == -1){ puts("-2");  continue; }
    if(res ==  3){ puts("0");   continue; }
    puts("0");
  }

  return 0;
}

C++: #include <cmath>
#include <iostream>

struct Circle2D {
	double x, y, r;
	static int Intersection(Circle2D &a, Circle2D &b);
};

int Circle2D::Intersection(Circle2D &a, Circle2D &b) {
	double diffABx = b.x - a.x, diffABy = b.y - a.y;
	double distanceCenterAB2 = diffABx * diffABx + diffABy * diffABy;
	double distanceCenterAB = sqrt(distanceCenterAB2);
	if (distanceCenterAB2 <= (a.r + b.r) * (a.r + b.r)) {
		if (a.r > b.r + distanceCenterAB) {
			return 2;
		}
		if (b.r > a.r + distanceCenterAB) {
			return -2;
		}
		return 1;
	}
	return 0;
}

int main() {
	int dataSet;
	Circle2D ca, cb;
	for (std::cin >> dataSet; dataSet > 0; --dataSet) {
		std::cin >> ca.x >> ca.y >> ca.r >> cb.x >> cb.y >> cb.r;
		std::cout << Circle2D::Intersection(ca, cb) << '\n';
	}
	return 0;
}

C++: #include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
int main(){
  double xa, ya, ra, xb, yb, rb;
  int n, ans;
  cin >> n;
  for(int i = 0; i < n; i++){
    cin >> xa >> ya >> ra >> xb >> yb >> rb;
    double d = sqrt( (xb-xa)*(xb-xa) + (yb-ya)*(yb-ya) );
    double r = ra + rb;
     
    if(d > r)
        ans = 0;
    else if(d <= r && d >= fabs(ra - rb))
        ans = 1;
    else{
      if(max(ra,rb) == ra)
        ans = 2;
      else
        ans = -2;
    }
    cout << ans << endl;
  }
}

C++: #define _USE_MATH_DEFINES

#include <iostream>
#include <string>
#include <sstream>
#include <iomanip>
#include <cmath>
#include <algorithm>
#include <utility>
#include <vector>
#include <numeric>

using namespace std;

struct Circle
{
	double x, y;
	double r;
};

int hit(Circle c0, Circle c1)
{
	double x = (c1.x - c0.x);
	double y = (c1.y - c0.y);

	double d = sqrt(x * x + y * y);
	if (d <= c0.r + c1.r)
	{
		if (c0.r + d < c1.r)
		{
			return -2;
		}
		else if (c1.r + d < c0.r)
		{
			return 2;
		}
		else
		{
			return 1;
		}
	}
	else
	{
		return 0;
	}
}

int main()
{
	int n;
	for (cin >> n; n--;)
	{
		Circle c0, c1;
		cin >> c0.x >> c0.y >> c0.r;
		cin >> c1.x >> c1.y >> c1.r;

		cout << hit(c0, c1) << endl;
	}
}

C++: #include<iostream>
#include<string>
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<cmath>
#include<utility>
#include<set>
#include<complex>
#include<map>
#define vi vector<int>
#define vvi vector<vector<int> >
#define ll long long int
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define ld long double
#define INF 1e9
#define EPS 0.0000000001
#define rep(i,n) for(int i=0;i<n;i++)
#define loop(i,s,n) for(int i=s;i<n;i++)
#define all(in) in.begin(), in.end()
#define MAX 9999999
using namespace std;
typedef pair<int, int> pii;
typedef pair<double,double>pdd;
int main(){
    pdd a,b; double ar,br; int n;
    cin>>n;
    rep(i,n){
        cin>>a.first>>a.second>>ar>>b.first>>b.second>>br;
        if((b.first-br<a.first-ar)&&(a.first+ar<b.first+br)//x
           &&(b.second+br>a.second+ar)&&(b.second-br<a.second-ar))return puts("-2")*0;
        swap(a,b); swap(ar,br);
        if((b.first-br<a.first-ar)&&(a.first+ar<b.first+br)//x
           &&(b.second+br>a.second+ar)&&(b.second-br<a.second-ar))return puts("2")*0;
        swap(a,b); swap(ar,br);
        if(abs(a.first-b.first)<(ar+br)&&max(ar,br)-min(ar,br)<abs(a.first-b.first))return puts("1")*0;
        swap(a.first,a.second); swap(b.first,b.second);
        if(abs(a.first-b.first)<(ar+br)&&max(ar,br)-min(ar,br)<abs(a.first-b.first))return puts("1")*0;
        puts("0");
        
    }
}

C++: #include <iostream>

int check_intersection(const double xa, const double ya, const double ra,
                            const double xb, const double yb, const double rb)
{
    double distance = (xa - xb) * (xa - xb) + (ya - yb) * (ya - yb);
    if(distance < ra || distance < rb){
        if(ra > rb)
            return 2;
        else
            return -2;
    }
    else if(distance > (ra + rb) * (ra + rb))
        return 0;
    else return 1;
}

int main ()
{
    double xa, ya, ra, xb, yb, rb;
    u_int N;
    
    std::cin >> N;
    for(u_int i = 0; i < N; ++i){
        std::cin >> xa >> ya >> ra >> xb >> yb >> rb;
        std::cout << check_intersection(xa, ya, ra, xb, yb, rb) << std::endl;
    }
    
    return 0;
}