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)
		distance := math.Sqrt((xb-xa)*(xb-xa) + (yb-ya)*(yb-ya))
		if rb+distance < ra {
			fmt.Println(2)
		} else if ra+distance < rb {
			fmt.Println(-2)
		} else if rb+ra >= distance {
			fmt.Println(1)
		} else {
			fmt.Println(0)
		}
	}
}

C++: #include <iostream>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <tuple>
#include <queue>
#include <set>
#include <cstdio>
#include <climits>
#include <cmath>
#include <array>
#include <functional>
#include <sstream>
#include <list>
#include <iomanip>
#include <set>
const int MOD=1000000007;
const int INF=1000000000;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
const double eps=1e-10;
const int inf=1e9;
typedef pair<int,int> P;
static const int COUNTER_CLOCKWISE=1;
static const int CLOCKWISE=-1;
static const int ONLINE_BACK=2;
static const int ONLINE_FRONT=-2;
static const int ON_SEGMENT=0;

class Point
{
public:
  double x,y;
  Point(double x,double y): x(x),y(y){}
  Point operator + (const Point &p)
  {
    return Point(x+p.x,y+p.y);
  }
  Point operator - (const Point &p)
  {
    return Point(x-p.x,y-p.y);
  }
  Point operator * (double k)
  {
    return Point(x*k,y*k);
  }
  Point operator / (double k)
  {
    return Point(x/k,y/k);
  }
  bool operator < (const Point &p) const
  {
    return x!=p.x ? x<p.x : y<p.y;
  }
  bool operator == (const Point &p) const
  {
    return fabs(x-p.x)<eps && fabs(y-p.y) < eps;
  }
  double abs(){return sqrt(norm());}
  double norm(){return x*x+y*y;}
};
typedef Point Vector;
double dot(Vector a,Vector b)
{
  return a.x*b.x+a.y*b.y;
}
double cross(Vector a,Vector b)
{
  return a.x*b.y - a.y*b.x;
}
double norm(Point a)
{
  return a.x*a.x + a.y*a.y;
}
double abs(Vector a)
{
  return sqrt(norm(a));
}
struct Segment
{
  Point p1,p2;
  Segment(Point p1,Point p2): p1(p1),p2(p2){}
};
typedef Segment Line;

class Circle
{
public:
  Point c;
  double r;
  Circle(Point c,double r):  c(c),r(r){}
};

typedef vector<Point> Polygon;


bool isorthogonal(Vector a,Vector b)
{
  return fabs(dot(a,b)-0.0)<eps;
}

bool isparallel(Vector a,Vector b)
{
  return fabs(cross(a,b)-0.0)<eps;
}
Point project(Segment s,Point p)
{
  Vector base=s.p2-s.p1;
  double r=dot(p-s.p1,base) / norm(base);
  return  s.p1 + base*r;
}
Point reflect(Segment s,Point p)
{
  return p+ (project(s,p)-p)*2.0;
}
double getdistance(Point a,Point b)
{
  return abs(a-b);
}
double getdistanceLP(Line l,Point p)
{
  return abs(cross(l.p2-l.p1,p-l.p1) / abs(l.p2-l.p1));
}
double getdistanceSP(Segment s,Point p)
{
  if(dot(s.p2-s.p1,p-s.p1) <0.0) return abs(p-s.p1);
  if(dot(s.p1-s.p2,p-s.p2) <0.0) return abs(p-s.p2);
  return getdistanceLP(s,p);
}

int ccw(Point p0,Point p1,Point p2)
{
  Vector a=p1-p0;
  Vector b=p2-p0;
  if(cross(a,b)>eps) return COUNTER_CLOCKWISE;
  if(cross(a,b)<-eps) return CLOCKWISE;
  if(dot(a,b)<-eps) return ONLINE_BACK;
  if(a.norm()<b.norm()) return ONLINE_FRONT;
  return ON_SEGMENT;
}
bool intersect(Point p1,Point p2,Point p3,Point p4)
{
  return (ccw(p1,p2,p3)*ccw(p1,p2,p4)<=0 && ccw(p3,p4,p1) * ccw(p3,p4,p2)<=0);
}
bool intersect(Segment s1,Segment s2)
{
  return intersect(s1.p1,s1.p2,s2.p1,s2.p2);
}
Point getcrosspoint(Segment s1,Segment s2)
{
  Vector base =s2.p2-s2.p1;
  double d1=abs(cross(base,s1.p1-s2.p1));
  double d2=abs(cross(base,s1.p2-s2.p1));
  double t=d1/(d1+d2);
  return s1.p1+(s1.p2-s1.p1)*t;
}

double getdistanceSS(Segment s1,Segment s2)
{
  if(intersect(s1,s2)) return 0.0;
  return min(min(getdistanceSP(s1,s2.p1),getdistanceSP(s1,s2.p2)),min(getdistanceSP(s2,s1.p1),getdistanceSP(s2,s1.p2)));
}

pair<Point,Point> getcrosspoints(Circle c,Line l)
{
  //assert(intersect(c,l));
  Vector pr=project(l,c.c);
  Vector e=(l.p2-l.p1)/abs(l.p2-l.p1);
  double base=sqrt(c.r*c.r - norm(pr-c.c));
  return make_pair(pr+e*base,pr-e*base);
}

double arg(Vector p){return atan2(p.y,p.x);}
Vector polar(double a,double r){return Point(cos(r)*a,sin(r)*a);}
pair <Point,Point> getcrosspoints(Circle c1,Circle c2)
{
  double d=abs(c1.c-c2.c);
  double a=acos((c1.r*c1.r+d*d-c2.r*c2.r) / (2*c1.r*d));
  double t=arg(c2.c-c1.c);
  return make_pair(c1.c+polar(c1.r,t+a),c1.c+polar(c1.r,t-a));
}
int contains(Polygon g,Point p)
{
  int n=g.size();
  bool x=false;
  for(int i=0;i<n;i++)
    {
      Point a=g[i]-p,b=g[(i+1)%n]-p;
      if(abs(cross(a,b)) < eps && dot(a,b)<eps) return 1;
      if(a.y>b.y) swap(a,b);
      if(a.y <eps && eps<b.y && cross(a,b)>eps) x=!x;
    }
  return (x ? 2 : 0);
}

Polygon andrewscan(Polygon s)
{
  Polygon u,l;
  if(s.size()<3) return s;
  sort(s.begin(),s.end());
  u.push_back(s[0]);
  u.push_back(s[1]);
  l.push_back(s[s.size()-1]);
  l.push_back(s[s.size()-2]);
  for(int i=2;i<s.size();i++)
    {
      for(int n=u.size();n>= 2 && ccw(u[n-2],u[n-1],s[i])!=CLOCKWISE; n--)
	{
	  u.pop_back();
	}
      u.push_back(s[i]);
    }
  for(int i=s.size()-3;i>=0;i--)
    {
      for(int n=l.size();n>=2&&ccw(l[n-2],l[n-1],s[i]) != CLOCKWISE;n--)
	{
	  l.pop_back();
	}
      l.push_back(s[i]);
    }
  reverse(l.begin(),l.end());
  for(int i=u.size()-2;i>=1;i--) l.push_back(u[i]);
  return l;
}
int main(int argc,char const* argv[])
{
  int n;
  cin >> n;
  for(int i=0;i<n;i++)
    {
      double ax,ay,ar,bx,by,br;
      cin >> ax >> ay >> ar >> bx >> by >> br;
      Point a=Point(ax,ay);
      Point b=Point(bx,by);
      Circle ca=Circle(a,ar);
      Circle cb=Circle(b,br);
      double dis=getdistance(a,b);
      if(ar-dis>eps) cout << 2 << endl;
      else if(br-dis>eps) cout << -2 << endl;
      else if(dis-ar>eps && dis-br>eps) cout << 0 << endl;
      else cout << 1 << endl;
    }
  return 0;
}

C++: #include <iostream>
//#include <algorithm>
//#include "math.h"

#define EPS 1.e-12

using namespace std;

int main(){
	int count;
	double xa,ya,ra,xb,yb,rb;
	cin >> count;
	for(int i=0;i<count;i++){
		cin >> xa >> ya >> ra >> xb >> yb >> rb;
		double dist2 = (xa-xb)*(xa-xb)+(ya-yb)*(ya-yb);
		//		double dist = (xa-xb)*(xa-xb)+(xa-xb)*(xa-xb);
		//cout << dist2 << " " << (ra+rb)*(ra+rb) << endl;
		//cout << ((dist2 -(ra+rb)*(ra+rb))>0) << endl;
		if(dist2>(ra+rb)*(ra+rb)+EPS){
			cout << 0 << endl;
		}
		else if(dist2 > (ra - rb)*(ra - rb)){
			cout << 1 << endl;
		}
		else if(ra>rb){
			cout << 2 << endl;
		}
		else{
			cout << -2 << endl;
		}
	}
}

C++: #include <iostream>

//2つの円の状態を調べる関数
int check_two_circles(const double xa, const double ya, const double ra,
					  const double xb, const double yb, const double rb);

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

int check_two_circles(const double xa, const double ya, const double ra,
					  const double xb, const double yb, const double rb){
	
	const double square_dist = (xa-xb)*(xa-xb)+(ya-yb)*(ya-yb);
	
	//(xa-xb)^2 + (ya-yb)^2 > (ra+rb)^2 ならば2つの円は重ならず離れている
	if(square_dist > (ra+rb)*(ra+rb)) return 0;
	//(xa-xb)^2 + (ya-yb)^2 < (ra-rb)^2 ならば片方の円がもう片方の中にある
	else if(square_dist < (ra-rb)*(ra-rb)){
		if(ra > rb) return 2;
		else return -2;
	}
	//いずれでもない場合，AとBは交わっている
	else return 1;
	
}

C++: #include <cstdio>
#include <cmath>
using namespace std;

int main(int argc, char *argv[]) {
	int dataN;
	scanf("%d", &dataN);
	for (int i = 0; i < dataN; i++) {
		float ax, ay, ra, bx, by, rb;
		scanf("%f %f %f %f %f %f", &ax, &ay, &ra, &bx, &by, &rb);
		double d = abs(ax-bx)*abs(ax-bx) + abs(ay-by)*abs(ay-by);
		d = sqrt(d);
		//printf("%f\n", d);
		if (d > ra+rb) puts("0");
		else {
			if (d < ra || d < rb) {
				if (ra > rb) puts("2");
				else puts("-2");
			}
			else puts("1");
		}
	}
	return 0;
}