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 <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 <math.h>
#include <stdio.h>
using namespace std;

double r(double x1,double y1,double x2,double y2){
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
	
	}

int main() {
	// your code goes here
	int n;
	double x1,x2,y1,y2,r1,r2;
	cin>>n;
	for(int j=0;j<n;j++){
		cin>>x1>>y1>>r1>>x2>>y2>>r2;
		
		if(r(x1,y1,x2,y2)>(r1+r2)){
			cout<<0<<endl;
		}
		else if(r(x1,y1,x2,y2)>=fabs(r1-r2)&&r(x1,y1,x2,y2)<=r1+r2){
			cout<<1<<endl;
		}
		else if(r1>r2){
			cout<<2<<endl;
		}
		else if(r2>r1){
		cout<<-2<<endl;	
		
		}
		
		
	}
	
	return 0;
}

C++: #include <iostream>
#include <queue>
#include <stack>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
#include <cmath>
#include <complex>
#include <map>
using namespace std;

#define rep(i,n) for(int i=0;i<int(n);++i)

static const double PI=6*asin(0.5);
typedef complex<double> P;
typedef long long ll;

double xa,ya,ra,xb,yb,rb;
int n;

double dist(P a,P b){
	return sqrt(real(a-b)*real(a-b)+imag(a-b)*imag(a-b));
}

int main(){
	cin>>n;
	rep(i,n){
		cin>>xa>>ya>>ra>>xb>>yb>>rb;
		P a(xa,ya), b(xb,yb);
		double r=dist(a,b);
		if(ra+rb<r) cout<<0<<endl;
		else if(ra>=rb+r) cout<<2<<endl;
		else if(rb>=ra+r) cout<<-2<<endl;
		else if(ra+rb>=r) cout<<1<<endl;
		
	}
	return 0;
}

C++: /*AOJ 0023*/

#include<iostream>
#include<vector>
#include<math.h>

using namespace std;

class Circle_obj{
public:
	double x,y,r;
};

int isCircleToCircle(Circle_obj a,Circle_obj b){

	double tmpX = a.x - b.x;
	double tmpY = a.y - b.y;

	double R = sqrt(tmpX*tmpX + tmpY*tmpY);

	if(a.r >= b.r){
		if( R + b.r <= a.r){
			return 2;
		}
	}
	else{
		if( R + a.r <= b.r ){
			return -2;
		}
	}

	if( R <= a.r + b.r){
		return 1;
	}
	else{
		return 0;
	}
}

int main(){

	int n;

	cin>>n;

	Circle_obj a,b;

	vector<int> data;

	for(int i=0;i<n;i++){
		cin>>a.x;
		cin>>a.y;
		cin>>a.r;
		cin>>b.x;
		cin>>b.y;
		cin>>b.r;

		cout<<isCircleToCircle(a,b)<<endl;

		//data.push_back(isCircleToCircle(a,b));
	}
	/*
	for(int i=0;i<n;i++){
		cout<<data.at(i)<<endl;
	}
	*/

	return 0;
}